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ABSTRACT: CTX-M-type enzymes are the most extensively distributed extended-spectrum β-lactamases (ESBLs) conferring resistance to third-generation cephalosporins in Enterobacteriaceae worldwide(3).…
Antimicrobial Agents and Chemotherapy 11/2012; · 4.84 Impact Factor
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ABSTRACT: Altered serum cobalamin concentrations have been observed in dogs with gastrointestinal disorders such as exocrine pancreatic insufficiency (EPI) or gastrointestinal inflammation. The aims of the current study were 1) to identify breeds with a higher proportion of dogs with a decreased serum cobalamin concentration, 2) to determine whether dogs with such decreased concentrations tend to have serum canine trypsin-like immunoreactivity (cTLI) concentrations diagnostic for EPI, and 3) to compare the number of submissions for serum cobalamin analysis by breed to the American Kennel Club (AKC) breed ranking list of 2009. In this retrospective study, results of 28,675 cobalamin tests were reviewed. Akitas, Chinese Shar-Peis, German Shepherd Dogs, Greyhounds, and Labrador Retrievers had increased proportions of serum cobalamin concentrations below the lower limit of the reference interval (<251 ng/l; all P < 0.0001). Akitas, Chinese Shar-Peis, German Shepherd Dogs, and Border Collies had increased proportions of serum cobalamin concentrations below the detection limit of the assay (<150 ng/l; all P < 0.0001). Akitas, Border Collies, and German Shepherd Dogs with serum cobalamin concentrations <150 ng/l were more likely to have a serum cTLI concentration considered diagnostic for EPI (≤2.5 µg/l; all P ≤ 0.001). The breed with the highest proportion of samples submitted for serum cobalamin analysis in comparison with the AKC ranking list was the Greyhound (odds ratio: 84.6; P < 0.0001). In Akitas and Border Collies, further investigations are warranted to clarify if a potentially breed-specific gastrointestinal disorder is responsible for the increased frequency of decreased serum cobalamin and cTLI concentrations.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 09/2012; · 1.21 Impact Factor
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ABSTRACT: The effective control of an outbreak of a highly contagious disease such as foot-and-mouth disease (FMD) in the United States will require a strong partnership between the animal agriculture industry and the government. However, because of the diverse number of economic, social, and psychological influences affecting livestock producers, their complete cooperation during an outbreak may not be assured. We conducted interviews with 40 individuals involved in the Texas cattle industry in order to identify specific behaviors where producer participation or compliance may be reduced. Through qualitative analysis of these interviews, we identified specific factors which the participants suggested would influence producer behavior in regard to FMD detection and control. Using the Theory of Planned Behavior (TPB) as an initial guide, we developed an expanded theoretical framework in order to allow for the development of a questionnaire and further evaluation of the relative importance of the relationships indicated in the framework. A 2-day stakeholder workshop was used to develop and critique the final survey instruments. The behaviors which we identified where producer compliance may be reduced included requesting veterinary examination of cattle with clinical signs of FMD either before or during an outbreak of FMD, gathering and holding cattle at the date and time requested by veterinary authorities, and maintaining cattle in their current location during an outbreak of FMD. In addition, we identified additional factors which may influence producers' behavior including risk perception, trust in other producers and regulatory agencies, and moral norms. The theoretical frameworks presented in this paper can be used during an outbreak to assess barriers to and social pressures for producer compliance, prioritize the results in terms of their effects on behavior, and improve and better target risk communication strategies.
Preventive Veterinary Medicine 10/2011; 103(2-3):120-35. · 2.05 Impact Factor
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ABSTRACT: Our objective was to summarize information on the diagnostic accuracy, in terms of test sensitivity (Se) and specificity (Sp), for bovine tuberculosis (bTb) tuberculin skin tests as currently used in the United States. Meta-analyses including Se and Sp estimates from field studies of bTb tuberculin tests conducted in North American cattle were conducted to provide a distribution of estimates and central tendency for Se and Sp of the caudal fold tuberculin (CFT) and serial interpretation of the CFT and comparative cervical tuberculin (CFT-CCT) tests. In total, 12 estimates for CFT and CFT-CCT test Se and Sp were identified from seven publications matching inclusion criteria. Estimates for CFT test Se ranged from 80.4% to 93.0% and CFT test Sp from 89.2% to 95.2%. Estimates for CFT-CCT test Se ranged from 74.4% to 88.4% and CFT-CCT test Sp ranged from 97.3% to 98.6%. These distributions of test Se and Sp are intended to provide a more realistic representation for U.S. bTb skin tests than previously reported. Estimation and discussion of herd-level CFT and CFT-CCT test parameters is also included. These results should be considered at the herd and individual animal level when evaluating results from tuberculin skin test results in North American cattle herds.
Preventive Veterinary Medicine 09/2011; 103(2-3):234-42. · 2.05 Impact Factor
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ABSTRACT: This study evaluates the effect of dietary protein content on renal parameters in 23 healthy spayed female cats. The objective was to determine if cats eating diets high in protein will have higher serum urea nitrogen (UN) and creatinine values without a detectable change in kidney function, as assessed by urinalysis. A single random cross-over design was used. Cats were fed a standard maintenance diet for at least 1 month prior to the dietary trial. They were fed in two phases. For the first phase, cats were randomly assigned to receive either a high protein [HP=46% metabolizable energy (ME)] or low protein (LP=26% ME) diet. For the second phase, cats were fed whichever diet they were not fed during the phase I period. Blood and urine samples were collected at 2-week intervals for the duration of the study (10 weeks). UN, albumin, alanine aminotransferase and urine specific gravity were significantly higher, and creatinine and phosphorus were significantly lower (P<0.05) when cats were fed the HP diet as compared to when they were fed the LP diet, although none of the mean values were found to be outside of the corresponding reference interval. Dietary intake can result in clinically significant changes in UN and statistically significantly changes in several other biochemical analytes, although all analytes are likely to remain within normal reference intervals. Therefore, an accurate dietary history is necessary to help determine if renal parameters are being influenced by diet in a particular patient.
Journal of feline medicine and surgery. 07/2011; 13(10):698-704.
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ABSTRACT: The incidence and severity of disease associated with toxigenic Clostridium difficile have increased in hospitals in North America from the emergence of newer, more virulent strains. Toxigenic C. difficile has been isolated from food animals and retail meat with potential implications of transfer to human beings. The objective of the present study was to determine the prevalence of C. difficile in pork from sausage manufacturing plants and retail meat in Texas. Twenty-three C. difficile isolates were detected from 243 meat samples (9.5%) from 3 sausage-manufacturing plants and 5 retail meat outlets from 2004 to 2009. Twenty-two isolates were positive for toxins A, B, and binary toxin, and were characterized as toxinotype V, PFGE type-NAP7, or "NAP7-variant." Susceptibilities to 11 antimicrobial agents in the current study were similar to those reported previously for toxinotype V isolates, although the results suggested somewhat reduced resistance than reported for other meat, animal, or human clinical toxinotype V isolates.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 07/2011; 23(4):807-11. · 1.21 Impact Factor
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ABSTRACT: Recently, an apparent rise in the number of cases attributed to community-acquired Clostridium difficile infection has led researchers to explore additional sources of infection. The finding of C. difficile in food animals and retail meat has raised concern about potential food-borne and occupational exposures. The objective of this study was to compare C. difficile isolated from a closed population of healthy individuals consisting of both humans and swine in order to investigate possible food safety and occupational risks for exposure. Using a multistep enrichment isolation technique, we identified 11.8% of the human wastewater samples and 8.6% of the swine samples that were positive for C. difficile. The prevalences of C. difficile in swine production groups differed significantly (P < 0.05); however, the prevalences in the two human occupational group cohorts did not differ significantly (P = 0.81). The majority of the human and swine isolates were similar based on multiple typing methods. The similarity in C. difficile prevalence in the human group cohorts suggests a low occupational hazard, while a greatly decreased prevalence of C. difficile in later-stage swine production groups suggests a diminished risk for food-borne exposure. The similarity of strains in the two host species suggests the possibility of a common environmental source for healthy individuals in a community setting.
Applied and environmental microbiology 07/2011; 77(16):5755-60. · 3.69 Impact Factor
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ABSTRACT: To determine current attitudes and practices related to pain and analgesia in cattle among US veterinarians in bovine practice and to identify factors associated with these attitudes and practices.
Web-based survey. Sample-3,019 US members of the American Association of Bovine Practitioners (AABP) with e-mail addresses.
Veterinarians were invited via e-mail to participate in a Web-based survey. Respondents replied to questions related to pain and analgesia and supplied personal, professional, and demographic information. Descriptive statistical analysis was performed, and associations among various factors were examined.
666 surveys (25.5% response rate) were analyzed. Among common procedures and medical conditions of cattle listed on the survey, castration of dairy calves < 6 months old was subjectively estimated as causing the least pain; abdominal surgery, toxic mastitis, and dehorning of calves > 6 months old were assessed as causing the greatest pain. Respondents reported not providing analgesic drugs to approximately 70% of calves castrated at < 6 months of age. The most commonly administered analgesics were NSAIDs, local anesthetics, and α(2)-adrenergic receptor agonists. Significant associations were detected among respondent characteristics and pain ratings, percentages of cattle treated, and opinions regarding analgesia.
Results provide information on current attitudes and practices related to pain and analgesia in cattle among US veterinarians in bovine practice and can be considered in the development of policies and protocols for pain management in cattle. These data can be compared with those of future studies to examine changes over time.
Journal of the American Veterinary Medical Association 03/2011; 238(6):755-67. · 1.79 Impact Factor
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ABSTRACT: The United States has been free of FMD since the 1920s. Faced with an incursion of FMD virus that might involve wildlife species, it is crucial that appropriate mitigation strategies be applied rapidly to control the disease. Disease spread models can be used to evaluate the design of optimal strategies. Using a previously developed susceptible-infected-recovered geographic automata model (Sirca) to simulate the spread of FMD through white-tailed deer populations in south Texas, we conducted a series of experiments to determine how pre-emptive mitigation strategies applied to white-tailed deer populations might impact the predicted magnitude and distribution of outbreaks following FMD virus incursion. Based on previously derived deer distributions in the two ecoregions found within the study area, simulated outbreaks were evaluated by comparing the median number of deer predicted to be infected and the median area predicted affected for a baseline scenario and 3 mitigation strategies: targeted cull, random cull and targeted depopulation buffer. Substantial differences were observed in the predicted magnitude of outbreaks both by mitigation strategy and by ecoregion: depending on the ecoregion, the creation of a targeted depopulation buffer could reduce the number of deer predicted infected by up to 52%, and the area affected by up to 31%. Results suggest that the outcome of an FMD incursion that involves wildlife species, such as white-tailed deer in south Texas, might depend on both where the incursion occurs and the type of pre-emptive mitigation strategy applied.
Preventive Veterinary Medicine 02/2010; 94(3-4):282-8. · 2.05 Impact Factor
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ABSTRACT: To compare apparent prevalence and patterns of antimicrobial resistance in Campylobacter spp in feces collected from pigs reared with antimicrobial-free versus conventional production methods in 8 states in the Midwestern United States.
Cross-sectional study.
95 swine farms that used antimicrobial-free (n = 35) or conventional (60) production methods.
Fecal samples from 15 pigs/farm were collected. Biochemical and multiplex-PCR analyses were used to identify Campylobacter spp. The minimal inhibitory concentrations of erythromycin, azithromycin, ciprofloxacin, nalidixic acid, gentamicin, and tetracycline for these organisms were determined by use of a commercially available antimicrobial gradient strip. The data were analyzed by use of population-averaged statistical models.
Campylobacter spp were isolated from 512 of 1,422 pigs. A subset (n = 464) of the 512 isolates was available for antimicrobial susceptibility testing. The apparent prevalence of Campylobacter spp isolates from pigs on conventional farms (35.8%) and antimicrobial-free farms (36.4%) did not differ significantly. Resistances to azithromycin, erythromycin, and tetracycline were significantly higher on conventional farms (70.0%, 68.3%, and 74.5%, respectively) than antimicrobial-free farms (20.1%, 21.3%, and 48.8%, respectively). Resistances to azithromycin, erythromycin, and tetracycline declined as the number of years that a farm was antimicrobial-free increased.
Production method did not affect the apparent prevalence of Campylobacter spp on swine farms. However, antimicrobial-free farms had a significantly lower prevalence of antimicrobial resistance. Although cessation of antimicrobial drug use will lower resistance over time, investigation of other interventions designed to reduce resistance levels is warranted.
Journal of the American Veterinary Medical Association 01/2010; 236(2):201-10. · 1.79 Impact Factor
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ABSTRACT: As concerns over the global spread of highly pathogenic avian influenza H5N1 have heightened, more countries are faced with increased surveillance efforts and incident response planning for handling a potential outbreak. The incorporation of molecular techniques in most diagnostic laboratories has enabled fast and efficient testing of many agents of concern, including avian influenza. However, the need for high-throughput testing remains. In this study, the use of a 384-well format for high-throughput real-time reverse transcription polymerase chain reaction (real-time RT-PCR) testing for avian influenza is described. The analytical sensitivity of a real-time RT-PCR assay for avian influenza virus matrix gene with the use of both 96- and 384-well assay formats and serial dilutions of transcribed control RNA were comparable, resulting in similar limits of detection. Of 28 hunter-collected cloacal swabs that were positive by virus isolation, 26 (92.9%) and 27 (96.4%) were positive in the 96- and 384-well assays, respectively; of the 340 hunter-collected swabs that were negative by virus isolation, 45 (13.2%) and 23 (6.8%) were positive in the 96- and 384-well assays, respectively. The data presented herein supports the utility of the 384-well format in the event of an avian influenza outbreak for high-throughput real-time RT-PCR testing.
Journal of veterinary diagnostic investigation: official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc 10/2009; 21(5):679-83. · 1.21 Impact Factor
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ABSTRACT: Modeling potential disease spread in wildlife populations is important for predicting, responding to and recovering from a foreign animal disease incursion such as foot and mouth disease (FMD). We conducted a series of simulation experiments to determine how seasonal estimates of the spatial distribution of white-tailed deer impact the predicted magnitude and distribution of potential FMD outbreaks. Outbreaks were simulated in a study area comprising two distinct ecoregions in South Texas, USA, using a susceptible-latent-infectious-resistant geographic automata model (Sirca). Seasonal deer distributions were estimated by spatial autoregressive lag models and the normalized difference vegetation index. Significant (P < 0.0001) differences in both the median predicted number of deer infected and number of herds infected were found both between seasons and between ecoregions. Larger outbreaks occurred in winter within the higher deer-density ecoregion, whereas larger outbreaks occurred in summer and fall within the lower deer-density ecoregion. Results of this simulation study suggest that the outcome of an FMD incursion in a population of wildlife would depend on the density of the population infected and when during the year the incursion occurs. It is likely that such effects would be seen for FMD incursions in other regions and countries, and for other diseases, in cases in which a potential wildlife reservoir exists. Study findings indicate that the design of a mitigation strategy needs to take into account population and seasonal characteristics.
Veterinary Research 02/2009; 40(3):18. · 4.06 Impact Factor
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ABSTRACT: In this article, we present a linked epidemiologic-economic modeling framework that is used to investigate several foot-and-mouth disease (FMD) mitigation strategies under the context of an FMD outbreak in a concentrated cattle-feeding region in the United States. We extend the literature by investigating the economic effectiveness of some previously unaddressed strategies. These include early detection, enhanced vaccine availability, and enhanced surveillance under various combinations of slaughter, surveillance, and vaccination. We also consider disease introduction points at a large feedlot, a backgrounder feedlot, a large grazing herd, and a backyard herd all in the Texas High Plains. To examine the economic implications of these strategies, we use a two-component stochastic framework. The first component is the epidemiologic model that simulates the spread of FMD as affected by control policies and introduction scenarios. The second component is an economic module, which calculates cattle industry losses and costs of disease control strategy implementation, and processes the results in a stochastic framework. The results show that early detection of the disease is the most effective mechanism for minimizing the costs of outbreak. Under some circumstances, enhanced surveillance also proved an effective strategy. Copyright 2009 Agricultural and Applied Economics Association
Review of Agricultural Economics. 01/2009; 31(4):931-950.
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ABSTRACT: To estimate associations between dietary factors and pancreatitis in dogs. Design-Retrospective case-control study.
198 dogs with a clinical diagnosis of pancreatitis and 187 control dogs with a diagnosis of renal failure without clinical evidence of pancreatitis.
Information on signalment, weight, body condition, dietary intake, medical history, diagnostic tests performed, concurrent diseases, treatments, duration of hospitalization, and discharge status was extracted from medical records. Information on dietary intake, signalment, weight, and medical, surgical, and environmental history was collected through a telephone questionnaire. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals.
On the basis of information extracted from the medical record, ingesting unusual food items (OR, 4.3) increased the odds of pancreatitis. On the basis of information gathered through the telephone questionnaire, ingesting unusual food items (OR, 6.1), ingesting table scraps the week before diagnosis (OR, 2.2) or throughout life (OR, 2.2), and getting into the trash (OR, 13.2) increased the odds of pancreatitis. Multivariable modeling indicated that reporting exposure to > or = 1 dietary factor during the telephone questionnaire (OR, 2.6), being overweight (OR, 1.3) or neutered (OR, 3.6), previous surgery other than neutering (OR, 21.1), and the interaction between neuter status and previous surgery other than neutering (OR, 0.1) were associated with the odds of pancreatitis.
Results suggested that dietary factors, being neutered, and previous surgery other than neutering increased the odds of pancreatitis in dogs.
Journal of the American Veterinary Medical Association 11/2008; 233(9):1425-31. · 1.79 Impact Factor
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ABSTRACT: Surveillance and monitoring are important for measuring the level of disease in a population, documenting changes in prevalence over time, determining high-risk areas for implementation of control measures, eradicating disease, and documenting freedom from disease. The documentation of freedom from disease has importance for international trade and the resumption of production after an outbreak. Johne's disease (JD) is an example of an endemic disease of cattle that has variable prevalence related to environmental and animal-level factors. Three methods of sample collection were used to describe the prevalence and distribution of JD seropositivity in Texas. Sampled cattle were: (1) extensively managed herds, (2) market cattle, and (3) clinically ill cattle examined by practicing veterinarians throughout Texas. Samples were evaluated for JD using a commercially available serum ELISA. Proportion of seropositive samples was compared and spatial distributions were evaluated for clustering. Difference of JD seropositivity was observed among the three sample populations suggesting that estimation of disease prevalence is dependant upon the source of samples.
Preventive Veterinary Medicine 09/2008; 86(1-2):1-7. · 2.05 Impact Factor
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ABSTRACT: To evaluate administration of chlortetracycline in feed of cattle as a method to select for tetracycline resistance among enteric bacteria in feedlot settings.
20 steers.
Steers were randomly assigned to an exposed cohort (n = 10) or an unexposed cohort (control cohort; 10). Chlortetracycline (22 mg/kg) in cottonseed meal was administered to the exposed cohort on days 0 through 4, 6 through 10, and 12 through 16. The control cohort was administered only cottonseed meal. Fecal samples were collected from 16 steers on days -7, 0, 2, 6, 8, 12, 14, 19, 22, 26, and 33, and Escherichia coli and Enterococcus spp were isolated. Minimum inhibitory concentration (MIC) of selected antimicrobials was estimated.
Overall, 56.0% and 31.4% of E coli and Enterococcus isolates, respectively, were resistant to tetracycline. Exposure to chlortetracycline was associated with a significant temporary increase in log(2) MIC for both genera but returned to preexposure values by day 33. Averaged across time, the proportion of tetracycline-resistant E coli and Enterococcus isolates was significantly greater in exposed than in unexposed steers. Although all ceftiofur-resistant E coli isolates were coresistant to tetracycline, exposure to chlortetracycline led to a significant decrease in the proportion of E coli resistant to ceftiofur during exposure.
Exposure to chlortetracycline was associated with a temporary increase in the likelihood of recovering resistant bacteria. Exposure to chlortetracycline decreased the likelihood of recovering ceftiofur-resistant E coli isolates, even though isolates were coresistant to tetracycline. These findings warrant further investigation.
American Journal of Veterinary Research 09/2008; 69(8):988-96. · 1.27 Impact Factor
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ABSTRACT: Exposure to environmental mycobacteria has been reported to be a factor contributing to false-positive results on bovine serological tests detecting antibodies to Mycobacterium avium subsp. paratuberculosis (Mptb). This study was conducted to investigate the association between recovery of mycobacteria from the environment of cattle and both (i) historically high or low seroprevalence to Mptb, and (ii) soil and water physicochemical characteristics. Eighty-two samples (soil and water) from nine beef cattle ranches in South-central and South Texas were assessed for the presence of mycobacteria. Twelve mycobacterial species were cultured from soil and water from four herds; no Mptb were detected in environmental samples. A positive culture of environmental mycobacteria from soil was significantly associated with lower pH and calcium as well as higher iron, zinc and manganese contents. Beef cattle are likely to be exposed to environmental mycobacteria that may contribute to false-positive results on ELISAs for Mptb infection. Exposure rates to these mycobacteria likely vary across small geographical areas and may be related to soil and/or water physicochemistry.
Veterinary Microbiology 10/2007; 124(1-2):153-9. · 3.33 Impact Factor
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ABSTRACT: To determine and compare levels and patterns of antimicrobial resistance among Escherichia coli isolated from pigs on farms that did not use antimicrobial agents versus pigs produced under conventional methods.
Cross-sectional study. Sample Population-35 antimicrobial-free and 60 conventional swine farms.
Farms were visited once, and fecal samples were collected from 15 finisher pigs if available. One E coli isolate from each sample was tested for susceptibility pattern to 14 antimicrobial agents by use of microbroth dilution.
E coli isolates were recovered from 1,381 (97.1%) of 1,422 fecal samples. Herd size was significantly larger for conventional swine farms. Resistance to ceftriaxone, ciprofloxacin, or nalidixic acid was not observed on any of the 95 farms. Three isolates from 2 conventional farms were resistant to ceftiofur. Conventional farms had significantly higher levels of resistance to ampicillin, sulfamethoxazole, tetracycline, and chloramphenicol, compared with antimicrobial-free farms. Fourteen percent of E coli isolates were susceptible or had intermediate resistance to all the tested antimicrobial agents. The 3 most frequent patterns of multiple resistance were streptomycin-tetracycline, sulfamethoxazole-tetracycline, and kanamycin-streptomycin-sulfamethoxazole-tetracycline.
Cessation of antimicrobial use did not appear to result in an immediate reduction in antimicrobial resistance in swine farms. Prospective studies of long-term antimicrobial usage and cessation are needed to estimate the extent to which food animal production may be contributing to antimicrobial drug resistance and might provide a direct measure of the rates of reversibility of antimicrobial drug resistance that might be achieved by curtailing antimicrobial usage.
Journal of the American Veterinary Medical Association 08/2007; 231(2):275-83. · 1.79 Impact Factor
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ABSTRACT: To determine effects of administration of ceftiofur crystalline-free acid (CCFA) on antimicrobial susceptibility of Escherichia coli in feedlot cattle.
61 feedlot steers.
A cohort study was conducted. Steers were housed in pens (5 pens with 10 steers and 1 pen with 11 steers). Five steers in each pen were administered CCFA, and 5 served as control steers (1 pen had 6 control steers). The CCFA administration included a single-dose regimen (6.6 mg/kg, SC, on day 0), two-thirds-dose regimen (4.4 mg/kg, SC, on day 0), and 3-dose regimen (6.6 mg/kg, SC, on days 0, 6, and 13). Fecal samples were collected on days 0, 2, 6, 9, 13, 16, 20, and 28. Fecal samples were collected immediately before CCFA administration. Minimum inhibitory concentrations of 15 antimicrobials were determined for 3 E coli isolates/fecal sample. Escherichia coli were enumerated by use of direct-plating techniques.
Resistance to 1 or more antimicrobials was detected in 986 of 1,441 (68.4%) isolates recovered. Administration of CCFA was associated with a transient increase in the population of ceftiofur-resistant isolates. Susceptibility returned to day 0 values (ie, samples collected immediately before CCFA administration) approximately 2 weeks after completion of CCFA administration. Agreement between ceftiofur resistance and co-resistance to ampicillin, chloramphenicol, streptomycin, sulfisoxazole, and tetracycline was almost perfect (kappa 0.97). We did not detect variation in susceptibility of E coli recovered from commingled control steers.
Administration of CCFA provided selection pressure that favored transient expansion of multiple-resistant variants.
American Journal of Veterinary Research 06/2007; 68(5):501-7. · 1.27 Impact Factor
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ABSTRACT: To evaluate the effect of exposure to environmental mycobacteria on results of 2 commercial ELISAs for paratuberculosis in cattle.
Experimental trial.
19 weaned crossbred beef calves.
Calves were inoculated SC with 1 of 5 mycobacterial isolates (3 calves/isolate) derived from herds with high proportions of false-positive serologic reactions for paratuberculosis, Mycobacterium avium subsp paratuberculosis (MAP; positive control inoculum; 2 calves), or mineral oil (negative control inoculum; 2 calves). Sera were assessed at intervals by use of 2 ELISAs (A and B) for paratuberculosis in cattle, and all calves underwent tuberculosis testing at the end of the study.
Neither mineral oil-inoculated calf had positive results with either ELISA during the study. Both MAP-inoculated calves were identified as seropositive via ELISA-A, and 1 calf was identified as seropositive via ELISA-B. By use of ELISA-A, > or = 1 false-positive reaction over time was detected in 2, 3, 3, and 1 of the 3 calves injected with Mycobacterium avium, Mycobacterium intracellulare, Mycobacterium scrofulaceum, or Mycobacterium terrae, respectively. By use of ELISA-B, only M scrofulaceum induced false-positive reactions (2/3 calves). Calves that had at least 1 positive ELISA-A result were more likely to be classified as suspect reactors via the caudal fold tuberculosis test.
False-positive serologic reactions may occur during use of commercially available ELISAs for paratuberculosis in calves experimentally exposed to environmental mycobacteria; naturally occurring exposures with these mycobacteria may represent a cause for high proportions of false-positive serologic reactions for paratuberculosis in some cattle herds.
Journal of the American Veterinary Medical Association 03/2007; 230(6):896-901. · 1.79 Impact Factor
