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Epidemiologic analysis of nosocomial Salmonella infections in hospitalized horses
Abstract
To examine the relationship between abdominal surgery and nosocomial Salmonella infections and the relationship between high caseload in combination with abdominal surgery and nosocomial Salmonella infections in hospitalized horses with signs of gastrointestinal tract disease.
140 horses.
Case-control study.
To accomplish the first objective, 1 to 4 control horses were matched with each nosocomial case horse on the basis of admission date of a primary case horse. The frequency of abdominal surgery and other investigated exposure factors were compared between nosocomial case horses and control horses. For the second objective, 4 control horses were matched with each nosocomial case horse on the basis of year of admission. The frequency of high caseload (>or=26 inpatients), abdominal surgery, and other factors was compared between nosocomial case horses and control horses.
The odds of nosocomial Salmonella infection were 8 times as high (odds ratio=8.2; 95% confidence interval=1.11, 60.24) in horses that underwent abdominal surgery, compared with the odds for horses that did not undergo surgery. High caseload alone or in combination with abdominal surgery was not associated with increased risk of nosocomial Salmonella infection.
Abdominal surgery was identified as a risk factor for nosocomial Salmonella infections in horses. Horses that undergo abdominal surgery require enhanced infection control and preventative care. Risk of nosocomial Salmonella infections may be reduced by implementation of biosecurity measures (such as the use of plastic boots, gloves, and footbaths) immediately after surgery.
... A recent survey reported that 84% of responding institutions have instituted an ICP overseen by a dedicated individual. 10 Salmonella shedding in hospitalized horses has been described, 7,[11][12][13][14][15] and identification of patients at risk for shedding Salmonella comprises the majority of patient surveillance efforts at many large animal hospitals. 10 Options for patient surveillance include predetermined interval sampling of patients perceived to be at increased risk for shedding Salmonella, or fecal sampling that is targeted by a set of clinical findings in a patient. ...
... 7,13,16 Those undergoing exploratory celiotomy have been reported in some studies to be at even higher risk for shedding. 13,14 With these observations in mind, a primary focus of our ICP has been the evaluation of horses admitted to our hospital with a presenting complaint of colic. ...
... There is great interest in attempting to differentiate between community-acquired and hospital-acquired infections, and various criteria based on time to appearance of first positive culture have been used to define nosocomial infection. 14,22 However, there is evidence to suggest that time to 1st positive sample does not correctly differentiate between hospital-acquired and community-acquired, hospital-expressed shedding. 28 Because of this, and the fact that expression of clinical signs is unlikely to be different regardless of the source, no attempt was made to differentiate between nosocomial and community-acquired infections. ...
Colic has been associated with shedding of Salmonella. Horses with salmonellosis typically develop diarrhea, fever, and leukopenia. Overlooking additional predictors may result in failure to detect shedding horses and increase environmental contamination.
Evaluate associations between signalment and clinicopathologic data during early hospitalization and Salmonella shedding in horses treated for acute colic.
Horses with acute colic admitted to a referral hospital. A total of 59 horses shedding Salmonella compared to 108 Salmonella-negative horses.
Retrospective case-control study evaluating patient and Salmonella culture data. Associations between variables and Salmonella shedding were identified using logistic regression. Two multivariable models were developed pertaining to (1) information available within 24 hours of admission and (2) clinical findings that developed later during hospitalization.
Variables retained for multivariable model 1 indicated that Warmbloods and Arabians had increased odds for shedding Salmonella, as did horses requiring surgery (OR, 2.52; 95% CI, 1.10-5.75) or having more severe gastrointestinal disease (OR, 2.59; 95% CI, 1.08-6.20). Retained variables for model 2 demonstrated that horses that were treated surgically (OR, 1.60; 95% CI, 0.70-3.62), developed fever >103°F (OR, 2.70; 95% CI, 0.92-7.87), had abnormal leukocyte count (OR, 1.38; 95% CI, 0.61-3.09), or became inappetent and lethargic (OR, 16.69; 95% CI, 4.08-68.24) had increased odds for shedding Salmonella.
In horses with acute colic that present without signs of diarrhea, fever, or leukopenia, additional predictors associated with shedding Salmonella could be used to more promptly identify horses likely to shed organisms.
... In general, most of the published articles on nosocomial outbreaks of Salmonella infections in hospitalised horses originated from veterinary hospitals located in North America (e.g. Hird et al. 1984Hird et al. , 1986Castor et al. 1989;Hartmann et al. 1996;Tillotson et al. 1997;Schott et al. 2001;Rankin et al. 2005;Ward et al. 2005a;Ekiri et al. 2009;Steneroden et al. 2010), but a few originating outside North America have also been reported (e.g. Amavisit et al. 2001). ...
... In a recent study (Ekiri et al. 2009), horses were classified as nosocomial Salmonella cases using the following criteria: Nosocomial cases were horses that tested negative for Salmonella in samples obtained at the time of admission and tested positive in samples collected Ն48 h after admission, and the primary case or source of nosocomial infection was an index case that had positive results for Salmonella in a sample collected at the time of admission, and shared the same serotype and antibiogram as the isolate from the nosocomial case, and there was an overlap between admission and discharge dates of the primary and nosocomial cases. Another source of nosocomial infection was environmental contamination. ...
... While bacteriological culture is the most common diagnostic procedure used for identification of horses infected with Salmonella, culture procedures are not standardised among veterinary microbiology laboratories (Hyatt and Weese 2004). For example, in a recent study (Ekiri et al. 2009), 1-2 g of fresh faeces were placed in 10 ml of selenite cystine broth (ratio, 1:10 to 1:5), and the broth was incubated at 37°C overnight for selective enrichment of Salmonella. This laboratory procedure differs from that reported in another study (House et al. 1999) in which investigators placed 5 g of fresh faeces in 100 ml of selenite broth (ratio, 1:20) and incubated the broth at 37°C overnight. ...
Outbreaks of nosocomial Salmonella infections in hospitalised horses can occur when surveillance and infection control protocols are not in place, or not well structured and enforced. The aim of this article is to present a review of published studies that have contributed to the literature of the epidemiology and infection control aspects of nosocomial Salmonella infections in hospitalised horses. The review highlights important elements that must be taken into consideration during the formulation, implementation and evaluation of a hospital surveillance and infection control programme designed to reduce the risk of an outbreak of nosocomial Salmonella infection in hospitalised horses.
... 4 Studies inconsistently report many factors that might be associated with animal shedding-some reporting an increased shedding risk associated with abdominal surgery, 5-8 diarrhea, [9][10][11] colic, 12 fever, 6,9 abnormal white count, 6,10 nasogastric intubation, 10,12 antimicrobial treatment, 7,12 a change in diet, 6,9 transportation, 10 age, 7 and breed 6 ; and others reporting no shedding risk associated with abdominal surgery, 9,10,12,13 fever, 7,10,13 abnormal white count, 7,9,13 nasogastric intubation, 6,9,13 antimicrobial treatment, [9][10][11] change in diet, 10 transportation, 7,13 or age, sex, and breed. 9,12,13 Some of these differences can be attributed to previous reports often targeting specific high-risk subgroups such as horses with colic [8][9][10] or diarrhea 8,9,12,14 ), or there use of intermittent sampling 5,15 from a limited time period (eg, 2-24 months) 5,9,10,15 Additionally, the majority of these reports concentrate on horses and do not evaluate the entire large animal hospital population. ...
... 4 Studies inconsistently report many factors that might be associated with animal shedding-some reporting an increased shedding risk associated with abdominal surgery, 5-8 diarrhea, [9][10][11] colic, 12 fever, 6,9 abnormal white count, 6,10 nasogastric intubation, 10,12 antimicrobial treatment, 7,12 a change in diet, 6,9 transportation, 10 age, 7 and breed 6 ; and others reporting no shedding risk associated with abdominal surgery, 9,10,12,13 fever, 7,10,13 abnormal white count, 7,9,13 nasogastric intubation, 6,9,13 antimicrobial treatment, [9][10][11] change in diet, 10 transportation, 7,13 or age, sex, and breed. 9,12,13 Some of these differences can be attributed to previous reports often targeting specific high-risk subgroups such as horses with colic [8][9][10] or diarrhea 8,9,12,14 ), or there use of intermittent sampling 5,15 from a limited time period (eg, 2-24 months) 5,9,10,15 Additionally, the majority of these reports concentrate on horses and do not evaluate the entire large animal hospital population. ...
Background:
Transmission of Salmonella in veterinary hospitals is typically associated with environmental contamination. Links between isolates recovered from hospitalized large animals and environment suggest animals as the likely source. Therefore, understanding factors influencing shedding is key in control. Shedding in hospitalized animals has been investigated, but many studies focused on subsets of animals limiting generalizability.
Objective:
(1) Investigate factors associated with fecal shedding of Salmonella among hospitalized large animals at a veterinary hospital. (2) Compare results obtained using 2 comparison groups for risk factor analysis-large animals with high confidence in negative shedding status and those with potential for misclassification of shedding status.
Animals:
Large animals admitted from March 2002 through December 2012.
Methods:
A case-control study was conducted among all hospitalized large animals that were routinely cultured as part of infection control efforts. Animal and hospital factors were evaluated. Data on factors of interest were collected retrospectively from electronic medical records. Multivariable conditional logistic regression was used to evaluate associations between animal factors and fecal shedding of Salmonella enterica.
Results:
During the study period, 5.9% (648/11 061) of hospitalized large animals were culture positive for Salmonella, with the majority being cattle (72%; 467/648) and horses (22%; 143/648). Although the odds of shedding varied by comparison group, overall, 69.4% of animal shedding could be attributed to systemic illness (population attributable fraction) in this study.
Conclusions and clinical importance:
Findings of this study inform our understanding of factors affecting Salmonella shedding in hospitalized large animals, thus improving our ability for implementation of evidence-based control measures.
... S. enterica is an important part of the microbial ecology of large veterinary hospitals, as has been particularly noted in publications regarding veterinary teaching hospitals [2][3][4][5][7][8][9][10]. In these large facilities, personnel tend to work in multiple areas (rather than individual areas) and many times the people most likely to contact patients are veterinary studentsgenerally considered to be novices with respect to patient management and infection control practices. ...
... Our imperfect understanding of Salmonella transmission in veterinary hospitals is typically based on snapshots of sample data that have been obtained during epidemics, or by use of targeted surveillance of animals (i.e., surveillance of high-risk groups) [9,10,12]. These data provide a very basic understanding suggesting that patients with severe GI disease (e.g., colic or diarrhoea) or other major systemic illness, and those that have experienced stressful situations are more likely to shed. ...
Healthcare-associated infections in veterinary hospitals are commonly attributed to Salmonella enterica, particularly in large animal facilities, and are characteristically associated with widespread environmental contamination. The objective of this study was to investigate factors influencing the likelihood of identifying environmental contamination of a veterinary hospital with S. enterica, while exploring different analytic methods to model complex factors that may influence this ecology. Environmental surveillance samples were collected in a large veterinary hospital as part of a long-term infection control programme. Data were collected retrospectively from the electronic medical records database. Many easily measured variables were complex in nature (i.e., they represented variance that is unmeasured or unidentified as a specific factor) necessitating the use of alternative analytic methods (variable cluster and principal components analyses) to provide perspective regarding the complex data structure and latent factors that may be contributing to this ecology. Subsequently, multivariable logistic regression was performed using generalised estimating equations. Results suggest the probability of detecting Salmonella in the environment increased as demand on personnel increased (e.g., in a busy hospital). Veterinary personnel need to remain vigilant in implementing practices that we believe empirically will mitigate risk for widespread environmental contamination and sustained transmission among patients (i.e., rigorous hygiene for personnel and the environment).
... As such, routine surveillance to detect this organism among equine cases is commonly performed on targeted high-risk subgroups (e.g. those with gastrointestinal disease) and upon recognition of epidemic disease [2,3], and less commonly performed continuously on all equine inpatients [4,5]. While there are many reports suggesting horses are more likely to shed Salmonella in their faeces at times of stress or systemic compromise [3,[5][6][7][8], there are few reports regarding endemic shedding and none that indicate whether risk factors may be different for susceptible versus MDR strains. ...
... those with gastrointestinal disease) and upon recognition of epidemic disease [2,3], and less commonly performed continuously on all equine inpatients [4,5]. While there are many reports suggesting horses are more likely to shed Salmonella in their faeces at times of stress or systemic compromise [3,[5][6][7][8], there are few reports regarding endemic shedding and none that indicate whether risk factors may be different for susceptible versus MDR strains. ...
Background:
Salmonella enterica is an important cause of healthcare-associated infections in veterinary hospitals - with outbreaks of multi-drug resistant (MDR) Salmonella among equine patients resulting in high case fatality rates and substantial financial cost.
Objectives:
Study objectives were to 1) investigate factors associated with shedding of MDR-Salmonella enterica; and 2) evaluate the effect shedding may have on health outcomes of previously hospitalised horses and their stablemates.
Study design:
Retrospective case-control study with prospective cohort study.
Methods:
Analysis of medical records (N=373; 94 culture-positive, 279 culture-negative) was undertaken to determine factors associated with shedding of MDR-Salmonella. Additionally, a follow-up study was conducted to assess long-term outcomes associated with shedding among previously hospitalised horses and their stablemates. Data regarding exposures of interest were collected retrospectively from medical records. Information on long-term outcomes was obtained by phone interview of owners. Multivariable regression techniques were used to investigate factors associated with shedding and subsequent health outcomes.
Results:
Horses experiencing diarrhoea during hospitalisation were more likely to shed Salmonella (OR 1.88; 95% CI 1.02, 3.45) compared to horses without diarrhoea, but isolates tended to be susceptible strains. Antimicrobial therapy during hospitalisation was not associated with shedding or recovery of MDR-strains. Shedding did not increase long-term risk for non-survival, colic or abnormal faeces after hospital discharge; nor increase risk for hospitalisation or occurrence of abnormal faeces in stablemates.
Main limitations:
Data collection was reliant upon the quality of medical records and owner recall which may have led to information bias. The study population was derived from central Kentucky and may differ from horse populations in other regions.
Conclusions and clinical importance:
In general, Salmonella shedding was not associated with decreased average survival times or impacts to health of stablemates, perhaps due to owner implemented biosecurity precautions. Regardless, recently hospitalised horses should be segregated after discharge, in addition to employing rigorous hygiene practices. This article is protected by copyright. All rights reserved.
... Such data can be used for the targeted development of prevention strategies to protect the horse from exogenous as well as endogenous infection sources [3]. In the past, severe infections with Gram-negative bacteria in hospitalized horses have generally been reported in association with Salmonella infections [8][9][10] and ESBL-producing Enterobacteriaceae [3,11]. Moreover, equine patients colonized or infected with Acinetobacter baumannii [12,13] might pose a risk for themselves or other patients within a clinical environment. ...
... Since they did not leave the hospital premises within that time, they were judged as horses with one day hospital stay. With this constraint, the average duration of hospital stay recorded for the colic group was 5,3 (median: 4) days and 13,2 (median: 10) for the open wound group. ...
Pathogens frequently associated with multi-drug resistant (MDR) phenotypes, including extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) and Acinetobacter baumannii isolated from horses admitted to horse clinics, pose a risk for animal patients and personnel. To estimate current rates of colonization, a total of 341 equine patients were screened for carriage of zoonotic indicator pathogens at hospital admission. Horses showing clinical signs associated with colic (n = 233) or open wounds (n = 108) were selected for microbiological examination of nostril swabs, faecal samples and wound swabs taken from the open wound group. The results showed alarming carriage rates of Gram-negative MDR pathogens in equine patients: 10.7% (34 of 318) of validated faecal specimens were positive for ESBL-E (94%: ESBL-producing Escherichia coli), with recorded rates of 10.5% for the colic and 11% for the open wound group. 92.7% of the ESBL-producing E. coli were phenotypically resistant to three or more classes of antimicrobials. A. baumannii was rarely detected (0.9%), and all faecal samples investigated were negative for Salmonella, both directly and after two enrichment steps. Screening results for the equine nostril swabs showed detection rates for ESBL-E of 3.4% among colic patients and 0.9% in the open wound group, with an average rate of 2.6% (9/340) for both indications. For all 41 ESBL-producing E. coli isolated, a broad heterogeneity was revealed using pulsed-field gel electrophoresis (PFGE) patterns and whole genome sequencing (WGS) -analysis. However, a predominance of sequence type complex (STC)10 and STC1250 was observed, including several novel STs. The most common genes associated with ESBL-production were identified as blaCTX-M-1 (31/41; 75.6%) and blaSHV-12 (24.4%).
The results of this study reveal a disturbingly large fraction of multi-drug resistant and ESBL-producing E. coli among equine patients, posing a clear threat to established hygiene management systems and work-place safety of veterinary staff in horse clinics.
... S. enterica is an important part of the microbial ecology of large veterinary hospitals, as has been particularly noted in publications regarding veterinary teaching hospitals [2][3][4][5][7][8][9][10]. In these large facilities, personnel tend to work in multiple areas (rather than individual areas) and many times the people most likely to contact patients are veterinary studentsgenerally considered to be novices with respect to patient management and infection control practices. ...
... Our imperfect understanding of Salmonella transmission in veterinary hospitals is typically based on snapshots of sample data that have been obtained during epidemics, or by use of targeted surveillance of animals (i.e., surveillance of high-risk groups) [9,10,12]. These data provide a very basic understanding suggesting that patients with severe GI disease (e.g., colic or diarrhoea) or other major systemic illness, and those that have experienced stressful situations are more likely to shed. ...
Healthcare-associated infections in veterinary hospitals are commonly attributed to Salmonella enterica , particularly in large animal facilities, and are characteristically associated with widespread environmental contamination. The objective of this study was to investigate factors influencing the likelihood of identifying environmental contamination of a veterinary hospital with S. enterica , while exploring different analytic methods to model complex factors that may influence this ecology. Environmental surveillance samples were collected in a large veterinary hospital as part of a long-term infection control programme. Data were collected retrospectively from the electronic medical records database. Many easily measured variables were complex in nature (i.e., they represented variance that is unmeasured or unidentified as a specific factor) necessitating the use of alternative analytic methods (variable cluster and principal components analyses) to provide perspective regarding the complex data structure and latent factors that may be contributing to this ecology. Subsequently, multivariable logistic regression was performed using generalised estimating equations. Results suggest the probability of detecting Salmonella in the environment increased as demand on personnel increased (e.g., in a busy hospital). Veterinary personnel need to remain vigilant in implementing practices that we believe empirically will mitigate risk for widespread environmental contamination and sustained transmission among patients (i.e., rigorous hygiene for personnel and the environment).
... Salmonella is a zoonotic organism, and a serious public and animal health concern (Singh et al., 2009). Salmonella is also an important nosocomial pathogen of hospitalized horses (Dargatz and Traub-Dargatz, 2004; Ekiri et al., 2009), responsible for enteric gastrointestinal diseases (Ernst et al., 2004). Although Salmonella is rarely detected in healthy horses (Pichner et al., 2005), Salmonellae remain major contributors to acute enteric disease, responsible for many cases of diarrhoea in horses (Kim et al., 2001). ...
... Horses admitted to hospitals are likely to be more at risk of Salmonella infection due to stressors, such as surgery, antibiotic therapy (Ernst et al., 2004) or a combination of these factors, (Ekiri et al., 2009) making them more likely to shed bacteria. Horses can be a source of infection with Salmonella and several studies have documented zoonotic transmission to humans (Hoelzer et al., 2011). ...
Aims: Equine hospital Salmonella spp. were investigated retrospectively using antibiotic resistance typing and macro-restriction pulsed field gel electrophoresis techniques.
Study Design: Retrospective study.
Place and Duration of Study: Department of Comparative Molecular Medicine and department of Animal and Population Health, School of Veterinary Science, University of Liverpool.
Methodology: Twenty four achieved Salmonella isolates of equine faecal origin, previously collected from a UK equine hospital, were serotyped, phagetyped and tested both for antimicrobial susceptibility, by disc diffusion (BSAC) and for genetic relatedness by XbaI I-PFGE.
Results: Most isolates were Salmonella typhimurium (n=21), including five DT104; two were Salmonella enteritidis, and one was untypeable. Sixteen isolates, including five Salmonella typhimurium DT104 isolates exhibiting the classic penta-resistance phenotype (ACSSuT), were characterized as multidrug resistant (MDR). Fourteen MDR isolates showed additional resistance to florfenicol, although no resistance to ciprofloxacin was detected. MDR isolates showed two dominant resistance phenotypes: ACTSSuFlo (N=8) resistant to ampicillin, chloramphenicol, tetracycline, trimethoprim, streptomycin, sulfamethoxazole and florfenicol and ACTTrSSuFlo (N=6) which is also resistant to trimethoprim. Dendrogram analysis identified eleven distinct genetic groups showing an overall similarity of 84%. The dominant resistance phenotypes were located mainly in two genetic groups: ACTSSuFlo isolates were all collected in the same year and were restricted to one clonal PFGE group showing >99.5% genetic similarity; ACTTrSSuFlo isolates were genetically more diverse with 4/6 clustering in a closely-related group showing 94% similarity.
Conclusion: These findings suggest that although some Salmonella infections were introduced to the hospital from outside, infections spreading within the equine hospital could also be a reservoir of MDR Salmonella zoonotic infections and play a role in the development and dissemination of antibiotic resistance.
... In addition, horses undergoing colic surgery are at increased risk for shedding Salmonella. 24 Evaluation of antimicrobial use in horses undergoing colic surgery and degree of adherence to accepted guidelines is warranted in this population of animals. The purpose of this retrospective study was to describe antimicrobial use in horses undergoing colic surgery and evaluate factors that influenced prescribing behavior. ...
... 37 Given concerns over the emergence of multidrug resistant bacteria in veterinary medicine, 1,14 antimicrobial administration should be evidence-based and risk-adverse, particularly, in a patient population that might be more susceptible to shedding Salmonella. 24 Postoperative complications associated with clinicians choosing to prolong or reinstitute therapy were fever and signs of incisional inflammation/infection. While these are logical drivers of prescribing pattern, documentation of the incorrect dose, inappropriate timing preoperatively, lack of intraoperative redosing, and continuation of antimicrobials well into the postoperative provides strong evidence of misguided antimicrobial prophylaxis. ...
Recommendations for antimicrobial prophylaxis for surgery are well-described in human medicine, but information is limited for veterinary practice.
To characterize antimicrobial use in horses undergoing emergency colic surgery.
A total of 761 horses undergoing emergency colic surgery (2001-2007).
Retrospective case review. Antimicrobial dose and timing, surgical description, and duration of treatment were collected from medical records. Associations between antimicrobial use and the occurrence of fever, incisional inflammation or infection, catheter-associated complications, or Salmonella shedding during hospitalization were analyzed using rank-sum methods and logistic regression.
A total of 511 (67.2%) horses received an inappropriate amount of drug preoperatively. Median time from preoperative dose to incision was 70 (IQR 55-90) minutes; median total surgery time was 110 (IQR 80-160) minutes. Seventy-three horses were euthanized under anesthesia because of poor prognosis. Of 688 horses, 438 should have been redosed intraoperatively based on the duration of surgery. Only 8 (1.8%) horses were redosed correctly. Horses remained on perioperative antimicrobials a median of 3 (IQR 2-4.5) days. Antimicrobial therapy was reinstituted in 193 (28.9%) horses, and median days of total treatment were 3.8 (IQR 2-6). Signs that led to reinstituting therapy were fever (OR 3.13, P = .001) and incisional inflammation/infection (OR 2.95, P = .001). Horses in which treatment was reinstituted had 2.3 greater odds of shedding Salmonella (P = .003). Increased surgical time was associated with longer duration of antimicrobial therapy (OR 1.02, P = .001).
Despite published recommendations regarding antimicrobial prophylaxis, compliance is poor; improvement might reduce postoperative complications.
... Surgical site infections (SSIs) lead to impaired wound healing and are a common problem in hospitalized horses especially after median laparotomy or traumatic injuries (Mair & Smith, 2005). They are often caused by multidrug-resistant pathogens (MDRPs), including methicillinresistant Staphylococcus aureus (MRSA), extended-spectrum betalactamase-producing Enterobacterales (ESBL-E) and Acinetobacter baumannii (Bergstrom et al., 2012;Boerlin et al., 2001;Cuny et al., 2006Cuny et al., , 2008Dallap Schaer et al., 2010;Damborg et al., 2012;Dargatz & Traub-Dargatz, 2004;Ekiri et al., 2009;Henninger et al., 2007;Seguin et al., 1999;Van den Eede et al., 2012;Weese & Lefebvre, 2007), which cannot only be found in the environment but may also be a part of the body's own microbiota (Weese, 2008). Further examinations of S. ...
Objective:
Evaluation of the role of indicator pathogens in equine surgical site infection (SSI) and other infection-promoting factors.
Study design:
Cross-sectional study.
Animals:
Horses presenting with an open injury or surgical colic during 1.5 years.
Methods:
A nasal swab and a faecal sample were collected from every patient upon admission. Furthermore, a wound swab was collected from wounds of injured horses. Details on the wounds and procedures were documented. Laparotomy incisions and injuries were monitored for signs suggesting infection.
Results:
In total, 156 horses presented because of a surgical colic (n = 48) or open injuries (n = 108). Thirteen surgical colic patients and three injured horses did not survive beyond 24 h, and four injured horses were discharged from the clinic at the day of admission. SSIs occurred in 31 (30.7%) injured horses and 11 (31.4%) horses after laparotomy. Regarding injuries, general anaesthesia increased the risk of developing a WI compared to sedation. Indicator pathogens were cultured from 29/42 SSI. In total, 10/11 infected laparotomy incisions and 19/31 injuries with SSI tested positive for multidrug-resistant pathogens (MDRPs) . Indicator pathogens were not detected at admission in any of the horses that developed incisional SSIs after laparotomy but were detected in two of the injured horses that developed SSIs.
Conclusion:
MDRPs were identified in almost 70% of the SSI. Less than 5% of the affected animals were colonized with the same pathogen before admission, indicating that colonization with MDR pathogens is only one of the crucial factors for the development of SSI.
Clinical significance:
Colonization with MDRP seems not to predispose horses to MDR SSIs.
... Outbreaks in horses are characterised by high morbidity and mortality rates, nosocomial transmission to other patients, zoonotic transmission to hospital personnel, and even closure of facilities. Horses undergoing abdominal surgery are particularly at risk of developing nosocomial Salmonella infections (Ekiri et al. 2009). However, a recent study identified that Salmonella-positive horses which survived to discharge from the hospital after colic surgery had similar risks of long-term complications (e.g. ...
The growing problem of antimicrobial resistance affects veterinarians on a daily basis. Antimicrobial stewardship and responsible prescribing are essential for a future with effective antimicrobials, as it is unlikely that new antimicrobials will become available for use in horses in the near future. Extended‐spectrum β‐lactamase (ESBL) producing Enterobacteriaceae, methicillin‐resistant Staphylococcus aureus (MRSA) and Salmonella spp. are pathogens of significant concern but there are also other opportunistic pathogens such as Pseudomonas spp., α‐haemolytic Streptococcus spp., Enterococcus spp. and Acinetobacter spp. which, due to their high intrinsic resistance, have limited treatment options in adult horses. It is essential that highest priority critically important antimicrobials such as ceftiofur, enrofloxacin, rifampicin and polymyxin B are used prudently in horses and ideally based on culture and antimicrobial susceptibility testing (AST). For example, the use of polymyxin B at a low anti‐endotoxic dose rather than at a higher antimicrobial dose in horses for the treatment of systemic inflammatory response syndrome is a potential driver for resistance to colistin (polymyxin E), an antimicrobial used as a last resort in the treatment of multidrug resistant (MDR) Enterobacteriaceae infections in humans. Serum procalcitonin levels are used in humans to distinguish noninfectious inflammatory conditions from inflammation caused by bacteria and other infectious agents and are also used to guide cessation of antimicrobial treatment. Although no such studies have been performed in horses, this or other markers may prove to be helpful in guiding antimicrobial treatment decisions in the future. Optimising sampling techniques and good communication with the microbiology laboratory are essential for generating the accurate culture and AST results that underpin appropriate antimicrobial use. Additionally, there is clearly a need for national and international harmonisation of laboratory methods in order to improve the reliability and consistency of results reported by different laboratories.
... revealing that clades 1 and 2 were more similar to one another (mean core SNP difference, 1,638.72 Ϯ 8.49) than clades 1 and 3 (8,165.04 Ϯ 10.91) or clades 2 and 3 (9,246.30 ...
Increasingly, outbreak investigations involving foodborne pathogens are difficult due to the interconnectedness of food animal production and distribution, and homogeneous nature of industry integration, necessitating high-resolution genomic investigations to determine their basis. Fortunately, surveillance and whole-genome sequencing, combined with the public availability of these data, enable comprehensive queries to determine underlying causes of such outbreaks. Utilizing this pipeline, it was determined that a novel clone of Salmonella Reading has emerged that coincided with increased abundance in raw turkey products and two outbreaks of human illness in North America. The rapid dissemination of this highly adapted and conserved clone indicates that it was likely obtained from a common source and rapidly disseminated across turkey production. Key genomic changes may have contributed to its apparent continued success in commercial turkeys and ability to cause illness in humans.
... Risk factors for infection include recent abdominal surgery, antimicrobial administration, transportation, gastrointestinal disease, immunosuppression, diet changes, respiratory disease, high ambient temperature, and general anesthesia. [9][10][11] Historically, a diagnosis of Salmonella colitis was made through identification of the organism on fecal culture, but it is only intermittently shed. Real-time quantitative polymerase chain reaction (qPCR) has largely replaced culture based on shorter time to results, increased relative sensitivity, and potentially fewer serial samples required to detect Salmonella. ...
Acute, infectious, diarrhea in adult horses is a major cause of morbidity and is associated with numerous complications. Common causes include salmonellosis, clostridiosis, Coronavirus, and infection with Neorickettsia risticii (Potomac horse fever). Treatment is empirical and supportive until results of specific diagnostic tests are available. Supportive care is aimed at restoring hydration, correcting electrolyte imbalances, and limiting the systemic inflammatory response. The mainstays of therapy are intravenous fluid therapy, electrolyte supplementation where necessary, nonsteroidal anti-inflammatory agents, and nutritional support. Specific therapies include colloid oncotic support, antibiotics, hyperimmune plasma, polymyxin B, pentoxifylline, probiotics, binding agents, gastroprotectants, laminitis prevention, and coagulation prophylaxis.
... for hospitalization, 5 antimicrobial administration, 5,8 and abdominal surgery. 8,9 Risk factors for salmonellosis in the general horse population are poorly understood. ...
OBJECTIVE To describe the antimicrobial resistance patterns of Salmonella isolates obtained from horses in the northeastern United States and to identify trends in resistance to select antimicrobials over time.
SAMPLE 462 Salmonella isolates from horses.
PROCEDURES Retrospective data were collected for all Salmonella isolates obtained from equine specimens that were submitted to the Cornell University Animal Health Diagnostic Center between January 1, 2001, and December 31, 2013. Temporal trends in the prevalence of resistant Salmonella isolates were investigated for each of 13 antimicrobials by use of the Cochran-Armitage trend test.
RESULTS The prevalence of resistant isolates varied among antimicrobials and ranged from 0% (imipenem) to 51.5% (chloramphenicol). During the observation period, the prevalence of resistant isolates decreased significantly for amoxicillin—clavulanic acid, ampicillin, cefazolin, cefoxitin, ceftiofur, chloramphenicol, and tetracycline and remained negligible for amikacin and enrofloxacin. Of the 337 isolates for which the susceptibility to all 13 antimicrobials was determined, 138 (40.9%) were pansusceptible and 192 (57.0%) were multidrug resistant (resistant to ≥ 3 antimicrobial classes). The most common serovar isolated was Salmonella Newport, and although the annual prevalence of that serovar decreased significantly over time, that decrease had only a minimal effect on the observed antimicrobial resistance trends.
CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that current antimicrobial use in horses is not promoting the emergence and dissemination of antimicrobial-resistant Salmonella strains in the region served by the laboratory.
... Studies that have conducted active surveillance for faecal shedding of Salmonella spp. in horses admitted with clinical signs of gastrointestinal disorders demonstrated that Salmonella spp. were isolated from the faeces of a large proportion of horses that did not develop clinical salmonellosis post operatively (43-74%) [108,116,117]. Molecular studies of the horse's hind gut microbiota provides evidence to suggest that colitis arises as a result of imbalance among the different microbial species in the gut (dysbiosis) rather than a disease caused by a single bacterial species [118]. ...
Changes in management of the surgical colic patient over the last 30 years have resulted in considerable improvement in postoperative survival rates. However, postoperative complications remain common and these impact negatively on horse welfare, probability of survival, return to previous use and the costs of treatment. Multiple studies have investigated risk factors for postoperative complications following surgical management of colic and interventions that might be effective in reducing the likelihood of these occurring. The findings from these studies are frequently contradictory and the evidence for many interventions is lacking or inconclusive. This review discusses the current available evidence and identifies areas where further studies are necessary and factors that should be taken into consideration in study design. This article is protected by copyright. All rights reserved.
... A recent study on veterinary teaching hospitals revealed that 31 (82%) out of 38 reported outbreaks of nosocomial infections during the five years prior to an interview, and nineteen (50%) hospitals reported that zoonotic infections had occurred during the last two years (Benedict et al., 2008). With respect to equine patients, nosocomial infections associated with hospitalized horses also gain increasing attention in the scientific community (Seguin et al., 1999;Boerlin et al., 2001;Dargatz and Traub-Dargatz, 2004;Cuny et al., 2006;Henninger et al., 2007;Weese, 2007;Cuny et al., 2008;Walther et al., 2008;Ekiri et al., 2009;Walther et al. 2009;Dallap Schaer et al., 2010;Bergstrom et al., 2012;Damborg et al., 2012;Van den Eede et al., 2012). Even failure of an infection control program (ICP) resulting in an outbreak of salmonellosis has been reported: A fatal series of infections of equine patients associated with an AmpC-beta-lactamase-producing and multi-drug resistant Salmonella enterica subsp. ...
Enterobacteriaceae such as Escherichia coli are common commensals as well as opportunistic and obligate pathogens. They cause a broad spectrum of infectious diseases in various hosts, including hospital-associated infections. In recent years, the rise of extended spectrum beta-lactamase (ESBL)-producing E. coli in companion animals (dogs, cats and horses) has been striking. However, reports on nosocomial infections are mostly anecdotic. Here we report on the suspected nosocomial spread of both ESBL-producing and non-ESBL-producing multi-drug resistant E. coli isolates in three equine patients within an equine clinic. Unlike easy-to-clean hospitalization opportunities available for small animal settings like boxes and cages made of ceramic floor tiles or stainless steel, clinical settings for horses are challenging environments for infection control programs due to unavoidable extraneous material including at least hay and materials used for horse bedding. The development of practice-orientated recommendations is needed to improve the possibilities for infection control to prevent nosocomial infections with multi-drug resistant and other transmissible pathogens in equine clinical settings.
... 7,9,37 In the course of epidemics, horses with severe disease, such as those with colic or undergoing abdominal surgery, are frequently identified as shedding Salmonella and likely contribute to ongoing environmental contamination and transmission among hospitalized patients. 7,9,51,52 Factors associated with endemic disease During outbreaks, there is typically widespread environmental contamination and it is common for patient and environmental isolates to be phenotypically similar (ie, serotype and antimicrobial susceptibility); this phenomenon has also been identified during times of endemic disease, suggesting animals to be a likely source for this contamination. 4,8,29,53 From experience consulting with different veterinary facilities, disseminated environmental contamination is a ubiquitous feature associated with nosocomial Salmonella transmission, 4,7,8 although use of insensitive sampling and culture methods can impair the ability to detect this important feature (Paul Morley, personal communication, June, 2014). ...
Infection control is achieved through all efforts used to prevent the introduction and limit the spread of contagious pathogens within a facility or population, with the goal of eliminating sources of potentially pathogenic microorganisms and to disrupt infectious disease transmission. Congregating animals from multiple sources, as occurs at veterinary hospitals, racetracks, equestrian events, and boarding and training facilities, increases the risk for transmission of infectious diseases such as salmonella. There is a recognizable standard of practice for infection control and due effort must be given to control and prevention of infectious disease transmission within animal populations and facilities.
... 5 In the course of epidemic disease, horses with severe disease (eg, colic or undergoing abdominal surgery) are frequently identified as shedding Salmonella and likely contribute to ongoing environmental contamination and transmission among hospitalized patients. [30][31][32][33] Recovery of genetically related Salmonella Infantis isolates during routine surveillance of patients and the hospital environment over an extended period of time suggests environmental persistence and ongoing transmission despite implementation of a rigorous ICP, emphasizing the importance of eliminating reservoirs for infection within the hospital environment. 34 ...
There is a recognizable standard of practice for infection control in veterinary medicine. Effort must be given to control and prevention of infectious disease transmission within a facility and among animal populations. In the critical care setting, patients typically have a high degree of systemic illness and immune compromise, are commonly subjected to invasive procedures and placement of indwelling devices, and frequently receive antimicrobials and gastric protectants. Every equine critical care unit is distinctive in its physical and operational features and the types of patients that are managed. Infection control programs must therefore be tailored to each facility's needs.
... Risk factors for nosocomial Salmonella infection among hospitalized horses include colic as the reason for admission (Hird et al. 1984, House et al. 1999, abdominal surgery (Ekiri et al. 2009), parenteral antimicrobial drug administration (Hird et al. 1984, House et al. 1999, nasogastric intubation (Hird et al. 1984), increased mean daily ambient temperature (House et al. 1999), and shedding of the same Salmonella serovar by other equine patients in the days prior to admission (House et al. 1999). The establishment of Salmonella transmission as nosocomial in origin requires a combination of historical, clinical, and laboratory data. ...
Abstract Nosocomial salmonellosis continues to pose an important threat to veterinary medical teaching hospitals. The objectives of this study were to describe an outbreak of salmonellosis caused by Salmonella enterica serovar Oranienburg within our hospital and to highlight its unique features, which can be used to help mitigate or prevent nosocomial outbreaks in the future. We retrospectively analyzed data from patients that were fecal culture-positive for Salmonella Oranienburg between January 1, 2006, and June 1, 2011, including historical, clinical, and pulsed-field gel electrophoresis (PFGE) data. Salmonella Oranienburg was identified in 20 horses, five alpacas, and three cows during this time frame, with dates of admission spanning the period from August, 2006, through January, 2008. We consider most of these patients to have become infected through either nosocomial or on-farm transmission, as evidenced by molecular subtyping results and supportive epidemiologic data. Interpretation of PFGE results in this outbreak was challenging because of the identification of several closely related Salmonella Oranienburg subtypes. Furthermore, a high percentage of cases were fecal culture-positive for Salmonella Oranienburg within 24 h of admission. These patients initially appeared to represent new introductions of Salmonella into the hospital, but closer inspection of their medical records revealed epidemiologic links to the hospital following the index case. Cessation of this outbreak was observed following efforts to further heighten biosecurity efforts, with no known cases or positive environmental samples after January, 2008. This study demonstrates that a Salmonella-positive culture result within 24 h of admission does not exclude the hospital as the source of infection, and it underscores the important role played by veterinary medical teaching hospitals as nodes of Salmonella infection that can promote transmission outside of the hospital setting.
... In all cases, this panel included culture for Salmonella spp. by selective enrichment in selenite cystine broth, 14 detection of viruses by electron microscopy and rotavirus ELISA, a detection of C. difficile toxin A and B by ELISA, b anaerobic culture for C. perfringens, detection of Cryptosporidium spp. by modified acid-fast stain, c and detection of gastrointestinal parasite ova by flotation. ...
Background:
Diarrhea is common in foals but there are no studies investigating the relative prevalence of common infectious agents in a population of hospitalized diarrheic foals.
Objectives:
To determine the frequency of detection of infectious agents in a population of hospitalized foals with diarrhea and to determine if detection of specific pathogens is associated with age, outcome, or clinicopathologic data.
Animals:
Two hundred and thirty-three foals < or = 10 months of age with diarrhea examined at a referral institution.
Methods:
Retrospective case series. Each foal was examined for Salmonella spp., viruses, Clostridium difficile toxins, Clostridium perfringens culture, C. perfringens enterotoxin, Cryptosporidium spp., and metazoan parasites in feces collected at admission or at the onset of diarrhea.
Results:
At least 1 infectious agent was detected in 122 foals (55%). Rotavirus was most frequently detected (20%) followed by C. perfringens (18%), Salmonella spp. (12%), and C. difficile (5%). Foals < 1 month of age were significantly more likely to be positive for C. perfringens (odds ratio [OR] = 15, 95% confidence interval [CI] = 3.5-66) or to have negative fecal diagnostic results (OR = 3.0, 95% CI = 1.7-5.2) than older foals. Foals > 1 month of age were significantly more likely to have Salmonella spp. (OR = 2.6, 95% CI = 1.2-6.0), rotavirus (OR = 13.3, 95% CI = 5.3-33), and parasites (OR = 23, 95% CI = 3.1-185) detected compared with younger foals. Overall 191 of the 223 foals (87%) survived. The type of infectious agent identified in the feces or bacteremia was not significantly associated with survival.
Conclusions and clinical importance:
In the population studied, foals with diarrhea had a good prognosis regardless of which infectious agent was identified in the feces.
Managing Salmonella in equine populations can be challenging due to the epidemiology of this disease. In particular, due to the range of clinical outcomes, the occurrence of subclinical infections, and intermittent shedding. This greatly affects the ability to detect shedding and can lead to widespread environmental contamination and transmission. The veterinary profession can reduce the risk to stablemates and their caretakers, while meeting their ethical obligation, by appropriately managing these risks within animal populations and environments.
Background:
Gastrointestinal disease has been associated with shedding of Salmonella with previous studies demonstrating that horses with colic have a higher risk of acquiring and shedding Salmonella organisms.
Objectives:
The purpose of this study was to determine the prevalence of and risk factors associated with Salmonella shedding in a colic population at a referral clinic.
Study design:
Retrospective case-control study.
Methods:
For each colic case that was positive for Salmonella (n=56), two colic cases (n=112) that tested negative for Salmonella, were enrolled as controls. Associations between variables and Salmonella shedding were identified using logistic regression. Univariate and multivariable models were developed pertaining to 1) presenting clinicopathological data and 2) clinical variables that developed during hospitalisation.
Results:
Of the equids presenting with colic, 1585/1917 had a sample submitted for Salmonella testing. Of these, 56 were positive for Salmonella yielding a prevalence of 3.5%. Equids shedding Salmonella were more likely to present in July (OR=7.2, 95% CI=1.63-32.13, p=0.009) and present with a history of fever (OR=53.5; 95% CI=2.57-1113.03; p=0.01), increased lactate (OR=1.6; 95% CI=1.14-2.29; p=0.007) and/or neutropenia (OR=0.79; 95% CI=0.65-0.97; p=0.02). Hospitalised equids shedding Salmonella were more likely to be febrile (OR=4.8; 95% CI=1.47-15.8; p=0.01) and 10 times more likely to develop reflux (OR=10.1; 95% CI=1.67-61.43; p=0.01) compared to colic controls.
Main limitations:
Retrospective nature of the study and bias inherent to the retrieval of data from medicals records cannot be discounted. Classifying Salmonella status based on a single sample may have resulted in misclassification bias.
Conclusions:
The prevalence of Salmonella shedding in this colic population was low compared to earlier reports. Certain predictors such as the development of a fever or reflux in hospitalised colic cases were associated with Salmonella shedding and may help the clinician to promptly identify horses likely to shed, thus helping institute effective use of barrier nursing precautions.
Zusammenfassung
Das Ziel dieses Reviews ist, die allgemein gültigen Hygienemaßnahmen im Pferdestall zusammenzufassen sowie aktuelle Empfehlungen bei Ausbruch relevanter Infektionskrankheiten zu liefern. Die allgemeine Sauberkeit, Handhygiene, stressarme Haltung sowie regelmäßige Entwurmungen und Impfungen gehören dabei zur Basishygiene im Pferdebestand. Wichtige Maßnahme in der Infektionsprävention stellen dabei die Quarantäne aller rückkehrenden oder neu eingestallten Equiden und das regelmäßige Waschen und Desinfizieren der Hände zur Reduktion der Übertragung von Krankheitserreger dar.
Die Erstellung eines Hygieneplans, welcher die allgemeinen Biosicherheitsregeln sowie die Vorgehensweise für den Fall eines Ausbruchs einer ansteckenden Erkrankung, Zoonose bzw. Infektion mit multiresistenten Erregern (MRE) festlegt, wird empfohlen. Bereits bei begründetem Verdacht auf eine dieser Erkrankungen sollten weitere, über die übliche Basishygiene hinausgehende Maßnahmen (inklusive Schutzkleidung, Flächen- und Gerätereinigung und Desinfektion sowie Isolation potenziell erkrankter Tiere) eingeleitet werden. Die erforderlichen diagnostischen Proben sollen möglichst zeitnah entnommen werden, um einen Krankheitsverdacht schnellstmöglich zu bestätigen. Die entsprechenden Schutzmaßnahmen sind dem Übertragungsrisiko der Infektionserreger und der Art ihrer potenziellen Übertragung anzupassen.
Neben dem „Lock-Down“ des ganzen Stalls, der Klinik oder des Turnier-/Veranstaltungsgeländes spielt die räumliche Trennung der Tiere eine wichtige Rolle. Ein „Ampelsystem“ wird empfohlen, bei dem kranke oder positiv getestete Pferde in die rote Gruppe eingeordnet werden („erkrankt“). Tiere mit möglichem Kontakt zum pathogenen Agens sollten der gelben Gruppe („verdächtig“) zugeteilt und regelmäßig auf Anzeichen der Erkrankung und Fieber kontrolliert werden. In der grünen Kategorie („unverdächtig“) befinden sich klinisch unauffällige Pferde ohne Kontakt zu erkrankten Tieren. Zwischen den räumlich getrennten Bereichen sollte die Schutzkleidung gewechselt werden und eine entsprechende Desinfektion stattfinden.
Alle erweiterten Hygienemaßnahmen sollten beibehalten werden bis alle Tiere negativ getestet wurden und keine Symptome der Erkrankung über eine ausreichend lange Zeit zeigen.
Salmonella is an important veterinary pathogen contributing to gastrointestinal disease in horses and foals. Hospital biosecurity is an important consideration in preventing transmission between cases and zoonotic transmission. The prevalence of salmonella in horses in equine hospitals has previously been reported in the United States and Australia. However, to date, it has not been reported in New Zealand. The aim of this study was to identify the prevalence of salmonella faecal shedding in at‐risk cases undergoing testing by repeated faecal culture or faecal PCR in an equine hospital in the North Island of New Zealand. Retrospective cohort study. Medical records from a 2‐year period (July 2018 to June 2020) were reviewed. Cases identified by the treating clinician as at‐risk of salmonella, and subsequently tested with repeated faecal culture (at least three samples) or faecal PCR were included for analysis. Descriptive analysis was used, and prevalence data reported with 95% confidence intervals. A total of 28 horses were included in the final analysis. The overall prevalence of salmonella in the study population was 10.7% (n = 3/28, 95% CI 3.1–25.9%). Small sample size (n = 28) and retrospective study design provide support for further investigation. The prevalence of salmonella in the study population is comparable to previous reports in the United States. Further research into the prevalence and risk factors associated with faecal shedding of salmonella in hospitalised horses in New Zealand is warranted.
Morbidity and mortality associated with colic surgery is higher than other surgical procedures. There is no doubt that the development of complications leads to an increase in mortality, with the most common reasons for death or euthanasia during the postoperative period being pain/colic and reflux or ileus. This chapter presents the definition, risk factors, pathogenesis, prevention, diagnosis, treatment, and expected outcome of the complications associated with postoperative colic patient. The complications covered are pain/colic, pyrexia, incisional complications, postoperative reflux and postoperative ileus, diarrhea, intravenous catheter‐associated complications, hemoperitoneum, enterotomy and enterectomy complications, septic peritonitis, postoperative intraperitoneal adhesions, metabolic complications, endotoxemis/SIRS and shock, and laminitis.
Concurrent separate human outbreaks of Salmonella enterica serotype Reading occurred in 2017-2019 in the United States and Canada, which were both linked to the consumption of raw turkey products. In this study, a comprehensive genomic investigation was conducted to reconstruct the evolutionary history of S. Reading from turkeys, and to determine the genomic context of outbreaks involving this rarely isolated Salmonella serotype. A total of 988 isolates of U.S. origin were examined using whole genome-based approaches, including current and historical isolates from humans, meat, and live food animals. Broadly, isolates clustered into three major clades, with one apparently highly adapted turkey clade. Within the turkey clade isolates clustered into three subclades, including an “emergent” clade that only contained isolates dated 2016 or later, including many of the isolates from these outbreaks. Genomic differences were identified between emergent and other turkey subclades suggesting that the apparent success of currently circulating subclades clade is, in part, attributable to plasmid acquisitions conferring antimicrobial resistance, gain of phage-like sequences with cargo virulence factors, and mutations in systems that may be involved in beta-glucuronidase activity and resistance towards colicins. U.S. and Canadian outbreak isolates were found interspersed throughout the emergent subclade and the other circulating subclade. The emergence of a novel S . Reading turkey subclade, coinciding temporally with expansion in commercial turkey production and with U.S. and Canadian human outbreaks, indicates that emergent strains with higher potential for niche success were likely vertically transferred and rapidly disseminated from a common source.
Importance
Increasingly, outbreak investigations involving foodborne pathogens are confounded by the inter-connectedness of food animal production and distribution, necessitating high-resolution genomic investigations to determine their basis. Fortunately, surveillance and whole genome sequencing, combined with the public availability of these data, enable comprehensive queries to determine underlying causes of such outbreaks. Utilizing this pipeline, it was determined that a novel clone of Salmonella Reading has emerged that coincides with increased abundance in raw turkey products and two outbreaks of human illness in North America. The rapid dissemination of this highly adapted and conserved clone indicates that it was likely obtained from a common source and rapidly disseminated across turkey production. Key genomic changes may have contributed to its apparent continued success in the barn environment, and ability to cause illness in humans.
Overgrowth of enteric clostridia in dysbiosis in horses with colic is presumed but scarcely investigated. The objective was to provide prevalence data of Clostridium difficile and Clostridium perfringens in horses with and without gastrointestinal disease in Switzerland, and investigate microbiota differences between C. difficile shedders and non-shedders.
Fecal samples were taken from healthy horses (n = 103), horses with colic (n = 98) and horses with diarrhea (n = 151). Colic horses were sampled on three days. Selective enrichment culture and molecular typing for C. difficile and C. perfringens was performed. Microbiota differences between horses with colic shedding (n = 7) and not shedding (n = 7) C. difficile were assessed using metagenomic sequencing.
The cumulative prevalence (19% C. difficile; 16% C. perfringens) was higher compared to single day samples (1–10% C. difficile; 3–8% C. perfringens, all p < 0.003). Horses with colic shed significantly more C. difficile (p < 0.001) but not C. perfringens (p = 0.09) compared to healthy horses. Prevalence in horses with diarrhea was 8% for both Clostridium species. There were no significant microbiota differences between C. difficile shedders and non-shedders with regards to relative abundance on any phylogenetic level, and alpha diversity. Limited differences were seen on LEfSE analysis and in beta diversity indices.
Multiple fecal samples should be taken when investigating shedding of enteric clostridia. As horses with colic shed more enteric clostridia compared to healthy horses special biosecurity protocols for horses with colic should be considered in hospitals. Differences in microbiota composition between C. difficile shedders and non-shedders were limited. Further studies on the role of dysbiosis in C. difficile are needed.
Objective:
To compare long-term outcome of Salmonella-positive versus Salmonella-negative horses discharged from hospital after colic surgery.
Study design:
Retrospective case-control.
Animals:
Horses discharged from the hospital after colic surgery. For each horse with positive culture for Salmonella enterica (SAL-POS, n = 59), at least 2 horses testing negative for S. enterica (SAL-NEG, n = 119) were enrolled.
Methods:
Owners were interviewed via phone at least 12 months after surgery regarding: (1) complications after discharge from the hospital; (2) duration of survival; and (3) return to prior or intended use. Association between immediate postoperative clinical variables such as Salmonella status and long-term measures of outcome was tested via ratios (odds ratio [OR]) and 95% confidence intervals. Data were analyzed for survival using a Cox proportional hazards model and for return to use using multivariable logistic regression.
Results:
SAL-POS horses had a higher OR of surgical site infection (2.7 [1.1-6.9] P = .027) and weight loss (6.8 [1.8-26.1] P = .002). At the time of follow-up, there were 53/56 (95%) SAL-POS and 99/118 (84%) SAL-NEG horses alive. The final multivariable model for nonsurvival included postoperative colic (hazard ratio 7.6 [2.8-19.2] P = .002) and the interaction between Salmonella status and duration of rectal temperature > 103°F postoperatively (SAL-POS 1.04 [1.01-1.07] and SAL-NEG 1.16 [1.06-1.25], P = .005). The majority of horses returned to their intended use regardless of their SAL-POS (38/50, 76%) or SAL-NEG (77/96, 80%, P = .498) status.
Conclusion:
Salmonella-positive horses that survive to discharge from the hospital after colic surgery have similar risks of long-term complications (colic/diarrhea), survival, and return to function than Salmonella-negative horses.
The normal development of the oral cavity depends largely on the organized growth of a synchronized embryologic process. Dental diseases are frequently overlooked as the single cause of cachexia. Equine dentistry is a regular service of practitioners to the equine industry. Esophageal diseases in the horse are relatively rare compared with diseases in other compartments of the gastrointestinal tract. Gastric rupture typically occurs at the greater curvature. Squamous cell carcinoma is the most common primary gastric neoplasm in horses. It arises from the nonglandular compartment of the stomach. The intestinal mucosa is the most important stratum for digestion and absorption of nutrients and water. The intestinal tract has its own specialized immune protection known as gut-associated lymphoid tissue (GALT). The vast majority of intestinal disorders are mechanical events related to anatomic peculiarities of the horse and are the main causes for equine colic.
This chapter focuses on educating readers to be proactive when it comes to biosecurity attentiveness to safeguard patients, clients, students, co-workers, animal companions, and the community from potential infectious agent(s). Disease control activities against infectious agents occur at four levels: individual, institutional, community, and global. The transmission of infectious agents requires three elements: a source (or reservoir) of the infectious agent, a susceptible host with a portal of entry receptive to the agent, and a mode of transmission for the agent. Before implementing disease prevention and control strategies, several issues need to be considered, including risk, feasibility, cost, and effectiveness. Prevention strategies for infectious diseases can be characterized by using the traditional concepts of primary, secondary, or tertiary prevention. Veterinary infection control plans must be written, posted, and continually enforced by a designated staff member in order to be effective in preventing infection transmission.
Importance of Biosecurity Components of a Biosecurity Program Biosecurity for the Hospitalized Equine Colic Patient Biosecurity for the Equine Colic Patient at Home References
The main objective of this study was to assess the diagnostic performance of a real-time polymerase chain reaction (PCR) assay for the detection of Salmonella in fecal samples collected from hospitalized horses with or without signs of gastrointestinal (GI) tract disease. The PCR assay used primers and a probe that targeted the invA gene of Salmonella. Assuming a sensitivity of 100% and a specificity of 96.6%, and a disease prevalence of 2%, 5%, and 10-15% in study horses, the PCR assay had a high (100%) negative predictive value, and a positive predictive value that ranged from 37% in horses without signs of GI disease that tested Salmonella culture-negative, to 60% in horses with signs of GI disease that tested Salmonella culture-negative, to 76-83% in horses with signs of GI disease that tested Salmonella culture-positive. This study provides evidence that the real-time PCR that targets the Salmonella invA gene can be used as a screening test for the detection of Salmonella in feces of hospitalized horses with signs of GI disease. Horses that test PCR-positive can be tested in series using bacteriologic culture to reduce false positive results or to provide additional data (e.g., antibiogram and serotyping data) that can be used to identify potential nosocomial Salmonella infections.
With the rising importance of nosocomial infections in equine hospitals, increased efforts with regard to biosecurity and infection control are necessary. This even more since nosocomial infections are often associated with multi-drug resistant pathogens. Consequently, the implementation of targeted prevention programs is essential. Since nosocomial infections are usually multifactorial events, realization of only a single measure is rarely effective to overcome nosocomial spread in clinical practice. Equine patients may be colonized at admission with multi-drug resistant pathogens such as methicillin resistant Staphylococcus aureus (MRSA) and/or extended spectrum beta lactamase-producing (ESBL-) Enterobacteriaceae. Regardless of their individual resistance properties, these bacteria are common and usually unnoticed colonizers of either the nasopharynx or the intestinal tract. Also viral diseases caused by equine herpesvirus 1 (EHV-1) and EHV-4 may reach a clinic by patients which are latently infected or in the incubation period. To prevent nosocomal outbreaks, achieve an interruption in the infection chain and to eradicate infectious agents from the hospital environment, a professional hospital management is necessary. This should be adapted to both the wide range of pathogens causing nosocomial infections and the individual needs of equine patients. Amongst others, this approach includes a risk classification of equine patients at admission and information/enlightenment of the animal owners at discharge. An efficient management of inpatients, a targeted hygiene management and clear responsibilities with respect to biosecurity together with a surveillance of nosocomial infections form the cornerstone of infection control in equine hospitals.
Objective:
To assess awareness, perceived relevance, and acceptance of surveillance and infection control practices at a large animal referral hospital among referring veterinarians and clients who sent horses to the facility for veterinary care.
Design:
Survey.
Sample:
57 referring veterinarians and 594 clients.
Procedures:
A 15-question survey targeting Salmonella enterica as an important pathogen of interest in horses was sent to clients who sent ≥ 1 horse to the University of Florida Large Animal Hospital for veterinary care during July 1, 2007, through July 1, 2011, and to veterinarians who had referred horses to the same hospital prior to July 1, 2011. Responses were summarized with descriptive statistics. The χ(2) test and the Wilcoxon rank sum test were used to examine associations among variables of interest.
Results:
Survey response rates were low (57/467 [12%] for veterinarians and 594/3,095 [19%] for clients). Significantly more (35/56 [63%]) veterinarians than clients (227/585 [39%]) were aware that the hospital operates a surveillance and infection control program. Most veterinarians (56/57 [98%]) and clients (554/574 [97%]) indicated that sampling and testing of horses to detect Salmonella shedding in feces at admission and during hospitalization was justified. In addition, on a scale of 1 (not important) to 10 (very important), veterinarians and clients indicated it was very important (median score, 10 [interquartile range, 8 to 10] for both groups) that a referral hospital operates a surveillance and infection control program.
Conclusions and clinical relevance:
Survey results indicated that awareness of hospital surveillance and infection control practices was higher among veterinarians than clients, and these practices were considered relevant and well-accepted among participant veterinarians and clients.
To determine time to first detection of Salmonella organisms in feces of animals after experimental infection PO and times to onset of diarrhea and pyrexia to evaluate a common method for identifying nosocomial infections on the basis of time of admission and onset of clinical signs (ie, the 3-day criterion).
Meta-analysis.
Cattle, horses, goats, and sheep experimentally infected PO with Salmonella enterica subsp enterica.
Online databases were searched for published reports describing results of experimental infection of cattle, horses, goats, and sheep PO with salmonellae. Time to detection of organisms in feces as well as to onset of diarrhea and pyrexia was noted. Analysis of covariance was used to examine relationships among these variables, host species and age, and Salmonella serovar and magnitude of infecting dose.
Forty-three studies met the criteria for inclusion. Time to detection of salmonellae in feces ranged from 0.5 to 4 days. Times to onset of diarrhea and pyrexia ranged from 0.33 to 11 days and from 0.27 to 5 days, respectively. Time to onset of diarrhea was related to host age and Salmonella serovar. No other associations were identified.
Time to detection of salmonellae in feces is unreliable for identifying hospital-acquired infections; a 3-day criterion will misidentify hospital- versus community-acquired infections. Relying on clinical indices such as times to onset of diarrhea and pyrexia to trigger fecal sampling for detection of Salmonella infection will increase the risk of environmental contamination and nosocomial spread because animals may begin shedding organisms in feces several days prior.
Nosocomial salmonellosis is an important problem for large animal veterinary teaching hospitals (VTHs).
To describe failure of an Infection Control Program (ICP) that resulted in an outbreak of salmonellosis caused by Salmonella Newport multidrug resistant (MDR)-AmpC at a large animal VTH.
Sixty-one animals identified with the outbreak strain of Salmonella.
Retrospective study: Data collected included signalment, presenting complaint, duration of hospitalization, discharge status, and financial information. Phenotypic and genotypic characterization was performed on Salmonella isolates.
The outbreak occurred despite an existing ICP; the ICP was reviewed and weaknesses identified. Routine patient surveillance was not performed before or during the outbreak; fecal sampling was triggered only by a patient algorithm based on clinical signs. Sixty-one animals were infected with the outbreak strain of S. Newport, and the majority were horses (n = 54). Case fatality rate was 36.1%. S. Newport isolates demonstrated high genetic similarity (Dice ≥ 0.96), and all had the MDR-AmpC phenotype. Environmental persistence of the organism necessitated complete hospital closure, extensive decontamination, and remediation of the facility. A paradigm shift in the relevance of biosecurity in a VTH and the establishment of a stringent ICP were integral components of successful hospital reopening.
An ineffective ICP resulted in a nosocomial outbreak caused by a MDR S. Newport in a VTH. Closure of a VTH affected all missions of the institution and had substantial financial impact (US$4.12 million).
The objectives of this study were to identify and characterize temporal clusters of bovine Salmonella cases at a veterinary medical teaching hospital and to determine which clusters were likely to have involved nosocomial transmission. Data on fecal Salmonella shedding status, serotype, and antimicrobial resistance were collected retrospectively for all cattle admitted to the Cornell University Equine and Farm Animal Hospital between January 1, 1996, and June 1, 2007. Pulsed-field gel electrophoresis (PFGE) was performed on all available isolates. Cluster analysis was used to identify temporal clusters of cases. A total of 5398 cattle were admitted during the study period; the prevalence of fecal Salmonella shedding among clinical suspects was 6.5%, whereas that among nonsuspects tested through routine surveillance was 2.5%. Eight temporal clusters (including 57 cattle) were investigated as possible outbreaks involving nosocomial transmission, ranging in size from 4 to 10 cases. All but one cluster were centered over the month of August or September. A total of 15 Salmonella serotypes were represented, with the most common being Typhimurium (33%), Newport (23%), and Agona (12%). Among the isolates available for PFGE analysis, there were 19 PFGE types represented. The majority of temporal clusters during the study period were not nosocomial in origin. However, two of the clusters were outbreaks directly resulting from nosocomial Salmonella transmission, based on case histories, serotype data, antimicrobial resistance patterns, and PFGE analysis. The clear seasonal pattern exhibited by these clusters underscores the need for heightened Salmonella vigilance during the late summer and early fall. The combination of statistical methods, routine bacteriologic data, and PFGE analysis is an effective means of conducting surveillance and outbreak investigations in a hospital setting.
The development of diarrhea among hospitalized horses is a major concern for equine veterinary hospitals and referral centers. It is a potential complication of hospitalization for surgical or medical procedures and can contribute to the morbidity and mortality of horses with gastrointestinal and non-gastrointestinal diseases. Unfortunately, it can be difficult to pinpoint the exact cause of acute diarrhea or colitis, and in most cases, the specific etiologic agent is presumptive or undetermined. This article discusses the major etiologic agents of diarrhea in hospitalized horses, considers factors that place hospitalized horses at special risk for diarrhea, and examines several infectious colitis outbreaks that have occurred at veterinary referral centers.
The association of feeding practices with the development of digestive disorders in horses has long been recognized, although the underlying mechanisms had been barely considered. The physiologic consequences of meal frequency may help to explain the relationship and prove to be of major significance in the induction of many conditions. Many Equidae kept for performance and leisure activities are fed high-energy, low-forage rations twice daily, with limited access to hay or grazing. Rapid ingestion of such meals stimulates a copious outpouring of upper alimentary secretions and results in transient hypovolemia (15% plasma volume loss). Subsequent activation of the renin-angiotensin-aldosterone system (RAAS) contributes to the preservation of circulatory status. Large meals may accelerate digesta passage to the cecum and, thereby, increase soluble carbohydrate availability for large intestinal fermentation. Intense periods of fermentation develop that require significant shifts of fluid into the colonic lumen. This is followed by net fluid absorption, which, in part, is dependent on postprandial increases of aldosterone. Potential consequences of these events include (1) imbalances in the RAAS response, which may promote conditions favorable to gastrointestinal disturbance, notably large intestinal impaction, and (2) changes in the gastrointestinal microflora, which may affect the intraluminal endotoxin pool and the population of enterotoxin-producing bacteria. In contrast to episodic feedings, similar changes are absent or greatly attenuated under simulated grazing conditions (for example, small, frequent meals). Thus, modification of management practices to facilitate a more continuous feeding pattern may significantly reduce the incidence of digestive problems in the stabled horse.
To identify risk factors for nosocomial Salmonella infections among hospitalized horses.
Longitudinal study.
1,583 horses hospitalized in an intensive care unit between January 1992 and June 1996.
Survivor functions were used to estimate time to shedding salmonellae for various Salmonella serotypes. Survival analysis was then used to determine how variables associated with patient management, environmental conditions, hospital conditions, and other disease processes affected the risk of nosocomial Salmonella infection.
78 horses shed Salmonella organisms: 35 shed Salmonella krefeld, 26 shed S typhimurium, and 17 shed other Salmonella serotypes. Mean time from admission to shedding was significantly longer for horses shedding S krefeld or S typhimurium than for horses shedding other Salmonella serotypes. Therefore, infection with S krefeld or S typhimurium was considered nosocomial. Seven variables were found to be significantly associated with risk of nosocomial Salmonella infection: mean number of horses in the hospital shedding S krefeld during the 4 days prior to and the day of admission, mean number of horses shedding S typhimurium during this period, a diagnosis of large colon impaction, withholding feed, number of days fed bran mash, duration of treatment with potassium penicillin G, and mean daily ambient temperature.
Results suggest that risk of nosocomial Salmonella infections is greater for horses with large colon impactions. In addition to implementing hospital protocols that minimize cross contamination between patients, strategies to reduce the risk of nosocomial Salmonella infection should include minimizing use of potassium penicillin G and regulation of environmental temperature in the hospital.
The interface between the organism and the outside world, which is the site of exchange of nutrients, export of products and waste components, must be selectively permeable and at the same time, it must constitute a barrier equipped with local defense mechanisms against environmental threats (e.g. invading pathogens). The boundaries with the environment (mucosal and skin surfaces) are therefore covered with special epithelial layers which support this barrier function. The immune system, associated with mucosal surfaces covering the largest area of the body (200-300 m(2)), evolved mechanisms discriminating between harmless antigens and commensal microorganisms and dangerous pathogens. The innate mucosal immune system, represented by epithelial and other mucosal cells and their products, is able to recognize the conserved pathogenic patterns on microbes by pattern recognition receptors such as Toll-like receptors, CD14 and others. As documented in experimental gnotobiotic models, highly protective colonization of mucosal surfaces by commensals has an important stimulatory effect on postnatal development of immune responses, metabolic processes (e.g. nutrition) and other host activities; these local and systemic immune responses are later replaced by inhibition, i.e. by induction of mucosal (oral) tolerance. Characteristic features of mucosal immunity distinguishing it from systemic immunity are: strongly developed mechanisms of innate defense, the existence of characteristic populations of unique types of lymphocytes, colonization of the mucosal and exocrine glands by cells originating from the mucosal organized tissues ('common mucosal system') and preferential induction of inhibition of the responses to nondangerous antigens (mucosal tolerance). Many chronic diseases, including allergy, may occur as a result of genetically based or environmentally induced changes in mechanisms regulating mucosal immunity and tolerance; this leads to impaired mucosal barrier function, disturbed exclusion and increased penetration of microbial, food or airborne antigens into the circulation and consequently to exaggerated and generalized immune responses to mucosally occurring antigens, allergens, superantigens and mitogens.
Exposure of ciprofloxacin- and cefepime-susceptible Pseudomonas aeruginosa isolates to increasing concentrations of ciprofloxacin selected for ciprofloxacin resistance in 26/27 and cefepime nonsusceptibility
in 7/27 isolates. Exposure of the isolates to increasing concentrations of cefepime selected for cefepime nonsusceptibility
in 20/27 isolates but not for ciprofloxacin resistance.
Previously, we have demonstrated that surgical stress rapidly induced transient hyporesponsiveness of blood cells to endotoxin and that monocyte mCD14 and HLA-DR expression decreased soon after the start of surgery under general anaesthesia. This study was designed to investigate the effects of epidural anaesthesia on surgical stress-induced immunosuppression in patients undergoing upper abdominal surgery.
After having obtained informed consent, patients were randomly allocated to receive general anaesthesia (Group G) or general anaesthesia with epidural anaesthesia (Group E). Perioperative changes in neutrophil phagocytic activity, neutrophil respiratory burst activity, monocyte mCD14 and HLA-DR expression, plasma IL-10 concentration, and the LPS-induced TNF-alpha production in whole blood were measured.
Surgical stress rapidly depressed neutrophil phagocytic activity, monocyte mCD14 and HLA-DR expression, and LPS-induced TNF-alpha production ex vivo (P < 0.05 vs preoperation) in both Group G and Group E. In contrast, the plasma IL-10 concentration increased significantly 2 h after the start of surgery (P < 0.05) in both groups. There were no significant differences between the two groups. The neutrophil respiratory burst activity did not change during the operation in either group.
This study showed that the innate immune system is suppressed from the early period of upper abdominal surgery. Subgroup analysis suggested that epidural anaesthesia to T4 dermatome as well as general anaesthesia may not protect patients from this immunosuppression. These results in part explain the impairment of host-defense mechanisms seen in the perioperative period.
In the past, CD14 has been viewed simply as a useful marker molecule for monocytes and macrophages. Now, new findings on its role in binding of LPS-LBP complexes and in signal transduction have engendered renewed interest in the properties of CD14. Here, CD14 function, its expression in different cell types and the regulation of expression, including the generation of soluble CD14, are described, and the diagnostic value of CD14 in various diseases is discussed.
Feces from 1,451 horses entering a veterinary hospital over a 13-month period were cultured for salmonella. A total of 46 horses (3.2%) yielded 1 or more salmonella-positive fecal cultures. Twenty horses were found to be excreting salmonella in the feces on admission, and 5 of these later had severe diarrhea associated with enteric salmonellosis. Abdominal surgery and other severe stresses were associated with all cases of severe enteric salmonellosis. Serotypes of salmonella isolated included Salmonella agona (15), S anatum (14), S typhimurium (7), S typhimurium var copenhagen (4), S infantis (2), S montevideo (1), S meleagridis (1), S drypool (1), and an unnamed Salmonella serotype (1). Seven deaths were attributed to 4 serotypes (S typhimurium, 3; S anatum, 2; S typhimurium var copenhagen, 1; and S montevideo, 1). A marked seasonal incidence is isolations was found with isolations highest in later summer to early fall and lowest in the spring. It was also found that horses can shed salmonella intermittently, and a minimal of 5 consecutive negative fecal cultures is recommended before considering a horse not to be infected with salmonella.
Monocyte human leukocyte antigen-DR (HLA-DR) expression has correlated closely with clinical outcome in severely injured patients at high risk for infection. Monocytes from 77 asymptomatic volunteers expressed HLA-DR antigen with minimal variability in respect to age, gender, race, time of day or year, or serum alcohol level. Patients who developed infection after elective laparotomy had a significantly lower mean percentage of monocytes expressing HLA-DR antigen and a lower mean fluorescent intensity than uninfected patients (p less than 0.05). Severely infected nonsurgical patients had significantly lower values than normal volunteers (p less than 0.01), and the mean fluorescent intensity of those who died from infection was significantly lower than that of those who survived (p less than 0.05). Patients on immunosuppressive regimens after renal transplantation had levels of HLA-DR expression similar to those of the volunteers. Monocyte HLA-DR expression was found to be a reliable marker of clinical infection and showed remarkable reproducibility within the normal uninfected study population.
Surgical stress animal models were established by performing laparotomies on mice. It was found that this type of stress could suppress the natural killer (NK) cytotoxicity and the proliferation of spleen cells induced by conA or lipopolysaccharide (LPS). Dynamic changes showed that the stress-mediated immunosuppression was reversible, as the responses to conA and LPS would be restored with time. The sensitivity to the stress-mediated suppression was different according to variations in immunological parameters. Furthermore, the macrophages in spleen were tested by isolation by the plastic-adherent procedure. The results showed clearly that these adherent cells (Plastic Adherent Cells, PAC) possessed an immunosuppressive effect on mitogen-induced lymphocyte proliferation in post-operative mice, but not in normal mice. Treatment of mice with indomethacin blocked the PAC-mediated immunosuppression. Surgical stress appeared to increase the level of prostaglandins, which in turn induced the production of suppressor PAC.
Diarrhoeal disease is a common problem in developing countries. As a result of recent advances in diagnostic methodology, the causative agents can now be identified in most cases of acute diarrhoeal diseases. Enteric bacterial pathogens are the common cause of gastroenteritis in developing countries. Appropriate uses of antibiotics in selected cases of diarrhoea will decrease symptoms or reduce faecal shedding of the organism and prevent spread of infection. Antimicrobial agents improve the diarrhoea associated with cholera, shigellosis, enteric fever, enterotoxigenic Escherichia coli, giardiasis, amoebiasis, and probably Vibrio parahaemolyticus, and enteropathogenic E. coli. Antibiotics have no role in the treatment of viral diarrhoea or uncomplicated salmonella gastroenteritis. Most of the diarrhoeal diseases are self-limited and the wrong choice of antimicrobial agents will worsen the symptoms. Treatment of gastrointestinal infections with antimicrobials will change intestinal microflora, promote the emergence of resistant strains and overgrowth of potential pathogenic bacteria and fungi. Risks and benefits should be considered before prescribing antimicrobial agents.
A case-control study to identify risk factors associated with isolation of Salmonella was accomplished, using data from records of horses hospitalized in the period July 1971 through June 1982. Horses in which nasogastric tubes were passed were at 2.9 times greater risk of having Salmonella isolated, compared with horses that did not undergo this procedure. Horses treated with antibiotics parenterally were at 6.4 times greater risk, and those treated with antibiotics orally and parenterally were at 40.4 times greater risk of developing salmonellosis, compared with horses not receiving such treatment. Horses admitted because of colic were 4.2 times as likely to have Salmonella isolated as those admitted for other reasons. Breed, age, and type of surgery did not appear to be risk factors. The risk factors identified and the magnitude of their association with Salmonella isolation were similar to those observed in a preceding study.
A base-line study of bacteria isolated from horses admitted to the Veterinary Medical Teaching Hospital during a 6-month period was performed to determine the extent of multiresistant nosocomial infections caused by gram-negative aerobic bacteria other than Salmonella spp. Results of this study indicated that 21.9% of the 105 horses from which cultures and sensitivities were available had developed nosocomial gram-negative aerobic infections, with high rates of resistance to gentamicin, kanamycin, and trimethoprim sulfadiazine, three of the most often prescribed antibiotics in this hospital. In addition, a prospective study of antibiotic-resistant bacteria of fecal origin was performed to determine whether there was a change in the degree of antibiotic resistance of a horse's intestinal flora while the horse was hospitalized. Bacterial culturing for gram-negative lactose fermenting bacteria was done on fecal specimens collected directly from the rectum on day 1 and day 7 of a horse's hospitalization. Susceptibility testing was done on each isolant. Of the 24 paired fecal specimens obtained, Escherichia coli and Klebsiella sp isolated on day 7 were resistant to a significantly higher number of antibiotics than day 1 isolants (P = 0.003, P = 0.043, respectively).
Seventeen ponies were infected with Salmonella typhimurium and then 15 were variously stressed by transportation and/or surgery and 9 were given oxytetracycline. Indications of Salmonella reactivation occurred in all the stressed ponies. Diarrhea due to a reactivation of the Salmonella infection did not develop until greater than 3 days after stress, although maximal shedding of organisms occurred within 24 hours. A neutropenia generally occurred within 24 hours after stress and lasted about 5 days. A rectal temperature greater than 39 C usually did not occur. An increase in serologic titer was noticed in about half of the ponies. Transportation had a major role in reactivating the Salmonella infection, and 1 pony died of peracute colitis. The use of oxytetracycline prolonged the excretion of Salmonella; therefore, this drug should not be used after stress, particularly transportation, in ponies that have diarrhea or are known to be Salmonella carriers.
In an investigation of a 1981–1982 outbreak of nosocomial Salmonella saintpaul infection in hospitalized horses at the University of California Veterinary Medical Teaching Hospital in Davis, California,
a case-control study was performed using data gathered from the records of 33 cases and 132 controls. Multiple logistic regression
risk analysis was used to identify factors associated with isolation of the organism, controlling for the effects of other,
possibly confounding variables. Horses receiving parenteral antibiotics were at 10.9 times greater risk of having S. salntpaul isolated than were horses not receiving parenteral antibiotics. Horses intubated with nasogastric tubes were 3.9
times more likely to have had the organism isolated from fecal specimens than horses not intubated, and horses with a presenting
complaint of colic were at 2.2 times greater risk of isolation than horses with other presenting complaints.
The incidence of typhoid and paratyphoid in Singapore from 1976 to 1979 is reviewed. Common Vi-phage types were A, B1, B2, D1, D2 and E1. Most of the paratyphoid cases were imported but an outbreak of paratyphoid A started in 1979 for the first time in Singapore with a predominance of untypable phage type strains. Most of the strains of Salmonella typi and Salmonella paratyphi A & B were susceptible to antibiotics, except for 4 strains of S typhi isolated from imported cases. Infections caused by Salmonella typhimurium were most common in children under five. The strains were initially multiple-resistant to antibiotics, but gradually became more susceptible with decline in the number of cases. Among the salmonella serotypes isolated from clinical materials, Salmonella oranienburg showed multiple-resistance to antibiotics and started an outbreak among children in October 1978. A total of 55 serotypes other than salmonella typhimurium was isolated between 1976 and 1979, with most of them susceptible to the antibiotics except triple-sulpha.
Although previous studies have shown that simple laparotomy produces a depression in peritoneal macrophage (Mphi) antigen presentation capacity, it remains unknown whether the adverse effects of laparotomy are limited to peritoneal Mphi or whether such an insult also affects splenocyte immune function. To study this, mice were anesthetized and a 1-inch midline abdominal incision was made, followed by abdominal closure. At 2 and 24 hours after the surgical procedure, the animals were killed, splenocyte cultures established and stimulated for 48 hours with concanavalin A (2.5 micrograms/mL), while peritoneal macrophage cultures were stimulated with LPS (10 micrograms/mL). The proliferative capacity of the splenocytes, as well as their ability to release interleukin-2 and interleukin-3, was markedly decreased at 2 as well as 24 hours after laparotomy. Furthermore, the release of interleukin-6 by splenic and peritoneal macrophages from animals that underwent laparotomy were also significantly depressed at both 2 and 24 hours. These results support the concept that surgical stress in the form of midline laparotomy per se is sufficient to produce a significant impairment in cell-mediated immunity, thus setting the stage for increased incidence of postoperative complications.
In the past, CD14 has been viewed simply as a useful marker molecule for monocytes and macrophages. Now, new findings on its role in binding of LPS-LBP complexes and in signal transduction have engendered renewed interest in the properties of CD14. Here, CD14 function, its expression in different cell types and the regulation of expression, including the generation of soluble CD14, are described, and the diagnostic value of CD14 in various diseases is discussed.
Exposure to endotoxin produces a state of macrophage hyporesponsiveness on subsequent stimulation. Monocytes in patients with septic shock demonstrate a similar hyporesponsiveness to endotoxin. The purpose of this study was to examine whether this state of hyporesponsiveness extends to other inflammatory stimuli and the relationship of this state to cell surface receptor expression and the release of anti-inflammatory cytokines. Twelve normal volunteers, 10 patients with severe sepsis, and 9 patients with septic shock were included in the study. Monocytes from each subject were isolated and stimulated with lipopolysaccharide (LPS), staphylococcal enterotoxin B (SEB), and phorbol myristate acetate (PMA). Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) were measured in the supernatants by enzyme-linked immunosorbent assay (ELISA). Serum levels of transforming growth factor-beta1 (TGF-beta1), prostaglandin E2 (PGE2), and interleukin-10 (IL-10) were also measured by ELISA. The expression of monocyte CD14 and HLA-DR in whole blood were measured by flow cytometry. Patients with septic shock demonstrated significantly decreased TNF-alpha and IL-1beta release as compared with normal subjects in response to LPS. In response to SEB, patients with sepsis and patient with septic shock demonstrated significantly decreased release of TNF-alpha and IL-1beta. Significant decreases in TNF-alpha release were found in the patients with septic shock after PMA stimulation. There were no significant differences in the monocyte response to the different stimuli between patients with gram-positive sepsis and gram-negative sepsis. HLA-DR expression was significantly decreased in patients with septic shock (58 +/- 9 fluorescence units (flU)) as compared with normal subjects (102 +/- 14 flU) (p < 0.05). No differences in CD14 expression were observed. IL-10 levels were significantly increased in patients with sepsis (16 +/- 4 pg/ml) and in patients with septic shock (42 +/- 15 pg/ml) and were detectable in 1 normal subject. TGF-beta1 levels were decreased in patients with septic shock (25 +/- 6 pg/ml) as compared with those in normal subjects (37 +/- 2 pg/ml)(p < 0.05). PGE2 levels were significantly increased in patients with septic shock and patients with sepsis. These data are consistent with a more generalized monocyte hyporesponsiveness to bacterial toxins that may be related to altered cell surface receptor expression and the release of anti-inflammatory cytokines.
The effect of different fecal sample weights on the detection of Salmonella enterica in swine feces was examined. Sample weights evaluated were rectal swabs and fecal samples weighing 1 g, 10 g, and 25 g. Comparisons were made on matched fecal samples obtained from individual pigs housed on 2 commercial swine farms in North Carolina. Relative sensitivity (number of positive pigs per fecal weight category/number positive in all weight categories) increased (P < 0.001) with fecal sample weight, and ranged from 9% for rectal swabs to 78% for 25-g samples. Stomaching of fecal samples did not affect detection of S. enterica. These observations demonstrate that fecal sample weight can markedly influence estimates of prevalence of S. enterica in epidemiologic studies. Failure to consider the imperfect sensitivity of bacterial culture in the design and interpretation of epidemiologic studies will lead to underestimation of prevalence and reduced power to detect the presence of S. enterica-infected herds.
To evaluate factors potentially associated with fecal Salmonella shedding among equine patients hospitalized for colic at a veterinary teaching hospital and to determine the effects of probiotic treatment on fecal Salmonella shedding and clinical signs.
Longitudinal study and controlled trial.
246 equine colic patients.
History and medical information were obtained from patient records. Fecal and environmental samples were submitted for aerobic bacterial culture for Salmonella enterica. Fifty-one patients were treated with a commercially available probiotic; 46 were treated with a placebo. Logistic regression was used to evaluate data.
Salmonella organisms were detected in feces from 23 (9%) patients at least once during hospitalization. Patients were more likely to shed Salmonella organisms if diarrhea was evident < or = 6 hours after hospitalization and duration of hospitalization exceeded 8 days (odds ratio [OR], 20.3), laminitis developed during hospitalization (OR, 12.0), results of nasogastric intubation were abnormal (OR, 4.9), leukopenia was evident < or =6 hours after hospitalization (OR, 4.6), or travel time to the teaching hospital exceeded 1 hour (OR, 3.5). Horses treated with the probiotic did not differ from control horses in regard to likelihood of fecal Salmonella shedding (OR, 1.5) or prevalence of clinical signs.
Results suggest that certain risk factors are associated with fecal shedding of S enterica among equine patients hospitalized at a veterinary teaching hospital because of colic and that pathogen monitoring in patients and the hospital environment and use of barrier nursing precautions for equine colic patients are beneficial.
Between May 1996 and February 1997, 27 horses and a veterinary student at a veterinary teaching hospital developed apparent nosocomial Salmonella Typhimurium infection. The source of the multiple-drug resistant Salmonella Typhimurium was a neonatal foal admitted for treatment of septicemia. A high infection rate (approx 13% of hospitalized horses) coupled with a high case fatality rate (44%) for the initial 18 horses affected led to a decision to close the hospital for extensive cleaning and disinfection. Despite this effort and modification of hospital policies for infection control, 9 additional horses developed nosocomial Salmonella Typhimurium infection during the 6 months after the hospital reopened. Polymerase chain reaction testing of environmental samples was useful in identifying a potential reservoir of the organism in drains in the isolation facility. Coupled with clinical data, comparison of antimicrobial resistance patterns of Salmonella Typhimurium isolates provided a rapid initial means to support or refute nosocomial infection. Although minor changes in the genome of these isolates developed over the course of the outbreak, pulsed-field gel electrophoresis testing further supported that salmonellosis was nosocomial in all 27 horses.
Unlabelled:
It is generally accepted that major surgery is associated with severe alterations of the host-defense mechanisms. We investigated the effect of surgical stress on the immune system. Specifically, we studied the relationship between perioperative lipopolysaccharide (LPS) hyporesponsiveness and monocyte human leukocyte antigen-DR (HLA-DR) and CD14 expression during the perioperative period in 20 patients who underwent partial gastrectomy. This study demonstrated that surgical stress rapidly depressed monocyte mCD14 and HLA-DR expression in comparison with preanesthesia levels. Monocyte mCD14 expression recovered to preoperative levels on the first postoperative day, and monocyte HLA-DR expression recovered by the seventh postoperative day. Consistent with our previous study, LPS-induced tumor necrosis factor (TNF)-alpha production ex vivo was significantly suppressed from the beginning of the operation. On the contrary, the plasma interleukin-10 concentration started to increase after the surgical incision was made. LPS hyporesponsiveness was least at the end of the operation and returned to preoperative levels on the first postoperative day. In conclusion, the present study demonstrated that LPS responsiveness, plasma interleukin-10 concentration, and monocytes mCD14 and HLA-DR expression altered from the early period of surgery. These alterations may be related to the impairment of the immune system during the perioperative period.
Implications:
Recent studies demonstrate that surgical stress induces immune dysfunction. We found that surgical stress rapidly decreased monocyte mCD14 and human leukocyte antigen-DR expression, and endotoxin responsiveness. These findings suggest that early changes of the immune system caused by surgical stress contribute to postoperative complications such as sepsis and multiple organ failure.
The normal microflora acts as a barrier against colonisation of potentially pathogenic microorganisms and against overgrowth of already present opportunistic microorganisms. Control of growth of opportunistic microorganisms is termed colonisation resistance. Administration of antimicrobial agents, therapeutically or as prophylaxis, causes disturbances in the ecological balance between the host and the normal microflora. Most studies on the impact of antimicrobial agents on normal microflora have been carried out on the intestinal flora. Less is known on the effects on oropharyngeal, skin, and vaginal microflora. Disturbances in the microflora depend on the properties of the agents as well as of the absorption, route of elimination, and possible enzymatic inactivation and/or binding to faecal material of the agents. The clinically most common disturbances in the intestinal microflora are diarrhoea and fungal infections that usually cease after the end of treatment. A well-balanced microflora prevents establishment of resistant microbial strains. By using antimicrobial agents that do not disturb colonisation resistance, the risk of emergence and spread of resistant strains between patients and dissemination of resistant determinants between microorganisms is reduced. In this article, the potential ecological effects of administration of antimicrobial agents on the intestinal, oropharyngeal, and vaginal microflora are summarised. The review is based on clinical studies published during the past 10 years.
To estimate prevalence of and identify risk factors for fecal Salmonella shedding among hospitalized horses with signs of gastrointestinal tract disease.
Cross-sectional study.
465 hospitalized horses with gastrointestinal tract disease.
Horses were classified as positive or negative for fecal Salmonella shedding during hospitalization by means of standard aerobic bacteriologic methods. The relationship between investigated exposure factors and fecal Salmonella shedding was examined by means of logistic regression.
The overall prevalence of fecal Salmonella shedding was 13%. Salmonella serotype Newport was the most commonly isolated serotype (12/60 [20%]), followed by Anatum (8/60 [13%]), Java (13%), and Saint-paul (13%). Foals with gastrointestinal tract disease were 3.27 times as likely to be shedding Salmonella organisms as were adult horses with gastrointestinal tract disease. Adult horses that had been treated with antimicrobial drugs prior to hospitalization were 3.09 times as likely to be shedding Salmonella organisms as were adult horses that had not been treated with antimicrobial drugs prior to hospitalization. Adult horses that underwent abdominal surgery were 2.09 times as likely to be shedding Salmonella organisms as were adult horses that did not undergo abdominal surgery.
Results suggest that a history of exposure to antimicrobial drugs prior to hospitalization and abdominal surgery during hospitalization were associated with Salmonella shedding in adult horses with gastrointestinal tract disease. Foals with gastrointestinal tract disease were more likely to shed Salmonella organisms than were adult horses with gastrointestinal tract disease.
In some respects, the multitude of options for isolation of Salmonella and the lack of interlaboratory consistency make Salmonella isolation one of the most variable procedures in veterinary laboratories. Even with the vast number of techniques available, it seems that at least one or two new media become available every year that promise to be more sensitive, more specific,and more rapid. With all the potential media and techniques available, the diagnostic laboratory must choose those that efficiently and accurately give the timely results required clinically and epidemiologically. Many veterinary diagnostic laboratories have invested the time and effort to explore these options and usually have developed standard methods to ensure that their laboratory tests have high sensitivity and specificity. Clients have greater assurance in the accuracy of laboratory results if these standards and the process of deriving them are made available to them. Many laboratories participate in external quality assurance programs to demonstrate their ability to culture microorganisms accurately. These quality control programs are designed to ensure that the client receives the correct answers to questions that are vital for the treatment and health care of their horses. This important information is available only if the initial steps of collecting and shipping the samples have been executed appropriately.
In 1995, beta-lactam inhibitor combinations replaced third-generation cephalosporins as empirical therapy in an effort to manage extended-spectrum beta-lactamase (ESBL) resistance. This study investigated the relationship between antibiotic usage and ESBL organisms from 1994 through 2002 using epidemiological and molecular analysis.
A case-control study of 119 patients with ESBL organisms and 132 patients with non-ESBL organisms was conducted. Demographics, co-morbidities, device utilization and antibiotic use were analysed for all patients and infected patients only (cases = 75, controls = 83). Both exposure and degree of exposure (in grams) to antibiotics were included. A dot blot hybridization technique was used to identify genes in plasmid extracts from the ESBL organisms.
Ventilator days OR 1.1 (1.06, 1.15) P < 0.001, adult respiratory distress syndrome (ARDS) OR 3.1 (1.0, 9.7) P = 0.05, prior aminoglycoside use OR 2.7 (1.2, 6.1) P = 0.02, prior third-generation cephalosporin use OR 7.2 (2.6, 20) P < 0.001, and prior trimethoprim/sulfamethoxazole use OR 8.8 (3.1, 26) P < 0.001 were significantly associated with ESBL organisms by multivariate analysis. All models were concordant with a significant association of ventilator days, third-generation cephalosporins and trimethoprim/sulfamethoxazole with ESBL organisms. beta-Lactamase inhibitor combinations were not associated with ESBL organisms. Hybridization of plasmid extracts demonstrated that 95% of the ESBL organisms carried intI1, a mobile DNA element with a sulphonamide-resistance (R) gene and a frequent carrier of other R factors. Genes for specific types of trimethoprim-R and aminoglycoside-R were present in 26% and 40% of the extracts, respectively.
These data indicate that, besides patient risk factors and third-generation cephalosporins, other antibiotics may provide selective pressures in maintaining ESBL organisms due to multiple resistance genes on plasmids. beta-Lactamase inhibitor combinations appear to be an acceptable substitute to third-generation cephalosporins in strategies to control ESBL organisms.
To compare Salmonella enterica serotype Infantis isolates obtained from patients or the environment of a veterinary teaching hospital over a period of 9 years following a nosocomial outbreak to determine whether isolates were epidemiologically related or represented unrelated introductions into the hospital environment.
Fifty-six S. Infantis isolates were compared based on their phenotypic (antimicrobial drug [AMD] susceptibility pattern) and genotypic (pulsed-field gel electrophoresis [PFGE] pattern and presence of integrons) characteristics. Epidemiologically unrelated S. Infantis isolates clustered separately from all but two of the hospital isolates, and several isolates from different years and various sources were indistinguishable from each other in cluster analysis of two-enzyme PFGE results. A high percentage of isolates (80.3%) were resistant to at least one AMD, with 67.8% showing resistance to >5 AMD. The majority (74.1%) of isolates tested contained type 1 integrons.
Results strongly suggest that there was nosocomial transmission of S. Infantis during the initial outbreak, and that contamination arising from this outbreak persisted across years despite rigorous hygiene and biosecurity precautions and may have led to subsequent nosocomial infections.
Evidence of persistence and transmission of Salmonella clones across years, even in the face of rigorous preventive measures, has important implications for other facilities that have experienced outbreaks of Salmonella infections.
An outbreak of salmonellosis among horses at a veterinary teaching hospital
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The effects of colic on the microbial activity of the equine large intestine
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Nonparametric and distribution-free statistics
- Daniel
Risk factors for salmonellosis in hospitalized horses
- Hird
Effect of antimicrobial agents on the ecological balance of human microflora
- Sullivan