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Egg Production Systems and Salmonella in South America
Abstract
The growth of the poultry industry in South America has been explosive in recent years. More than 238 million layers are located in South America producing more than 4 million tons of eggs. Brazil, Argentina, and Colombia are the most important egg producers in this region. Nonenriched cage systems are not prohibited in South America and most of the laying hens are located in battery cage farms, which include automatic and conventional (manual) battery cage systems. Salmonella Gallinarum and Salmonella Enteritidis are the most prevalent serotypes in layer farms. South American countries have different regulations to control Salmonella in their flocks through various National Poultry Improvement Plans. This control is focused on S. Gallinarum biovars Gallinarum and Pullorum, S. Enteritidis, S. Typhimurium, and S. Heidelberg. Inactivated (killed) and attenuated (live) vaccines are available to control Salmonella spp. in poultry in South America, but there are some differences in licensed vaccines.
... In Europe, these two Salmonella serovars, Enteritidis and Typhimurium, are specifically regulated in laying flocks in all member states [9]. In Argentina, S. Enteritidis and S. Typhimurium represented more than 50% of foods contaminants from 2000 to 2005, and since 2006, S. Typhimurium has been the most frequent serotype isolated from humans, animals, and foods [10]. Nevertheless, the exact cause of the predominance of these Salmonella serovars is not yet clearly understood [11]. ...
... In South American countries, layers are commonly vaccinated with the 9R vaccines against fowl typhoid caused by S. Gallinarum [10]. Furthermore, cross-protection by the 9R vaccine against S. Enteritidis was reported as both serovars belong to the same serogroup [53]. ...
Worldwide, poultry infections by Salmonella are the cause of significant economic losses, not only due to reduced production (due to fowl typhoid disease), but also considering the efforts and control measures that must be constantly applied, especially due to zoonotic serovars. Poultry is a common reservoir of Salmonella and its transmission into the food chain is a risk for humans. The vaccination of layers plays an important role in the overall efforts to prevent Salmonella infections. An inactivated trivalent vaccine was prepared with S. Enteritidis, S. Typhimurium, and S. Infantis strains. Infection trials were performed to evaluate the efficacy of three vaccination schedules using inactivated and live S. Gallinarum 9R vaccines. For this purpose, at week 5 of life, one subcutaneous dose of live S. Gallinarum 9R vaccine (1–5 × 107 CFU) was given to Groups 1 and 2. At weeks 8 and 11 of life, chickens were also vaccinated with one (Group 1) or two (Groups 2 and 3) intramuscular doses of the inactivated oil-adjuvant trivalent vaccine (1 × 108 CFU/dose of each antigen). Group 4 consisted of chickens that remained unvaccinated (control). At week 14 of life, the efficacy of the vaccination plans was evaluated in three separate inoculation trials with S. Enteritidis, S. Typhimurium, or S. Infantis. After vaccination with the inactivated vaccine, homologous antibody production was observed, and after challenge, a significant reduction in the faecal shedding, invasion, and colonization of S. Typhimurium and S. Infantis was achieved by all vaccination schedules, while the vaccination with at least one dose of the live S. Gallinarum 9R vaccine was necessary to obtain such a significant protection against S. Enteritidis infection.
... The intense international market in food of animal origin facilitates the dissemination of variable strains of Salmonella spp. This context receives greater prominence when considering its relevance in public health, being one of the main pathogens involved in food gastroenteritis, and in the economy of the poultry sector, due to the slaughter and disposal of positive flocks (ABPA, 2020;SVS, 2019;Soria et al., 2017). ...
The analysis of Salmonella in the feces and the birds’ environment is a way of monitoring the colonization in the flocks and verifying the need for the introduction of stricter controls, in such a way that the results of the tests should be known before being sent for slaughter. The polymerase chain reaction (PCR), as well as other rapid methods represent alternatives increasingly used to detect enteric pathogens, but they need proof of effectiveness for their wide use. The aim of this study was to evaluate the equivalence between the results obtained by the methods: real-time PCR (BAX® System), Modified Rappaport-Vassiliadis Semi-solid Medium (MSRV) (ISO 6579) and the traditional method of official reference in Brazil for research of S. Typhimurium and S. Enteritidis in poultry samples. Two hundred and fifty-two samples of disposable shoe covers (DSC) and 252 samples of feces were infected with an average of 2 to 3 log CFU/g of each serovar, and the same samples without fortification were evaluated by the three methods. Five hundred and four diagnoses were obtained with satisfactory results in terms of repeatability (greater than 80%), reproducibility (mean 83,1%), sensitivity (81% to 100%), specificity (95% to 100%), and accuracy (90% to 100%). The compliance test verified that there was not a significant difference between the alternative and the official methods, allowing us to state that the methodologies have had equivalent performances.
Salmonellosis caused by Salmonella Enteritidis is a widespread zoonosis and poultry products are an important source of infection. This study was carried out to evaluate the protection of different vaccination schedules in layers using a live commercial attenuated Salmonella Enteritidis vaccine based on strain Sm24/Rif12/Ssq (AviPro® Salmonella Vac E, ELANCO) during rearing and egg production. Three hundred and fifty Salmonella-free chickens were distributed into 7 vaccinated groups and 1 unvaccinated group. Different vaccination schedules were performed combining either 1, 2, or 3 oral gavage doses. Chickens from Group A, B, and C were vaccinated once, either at the first day, at 7 or 16 wk old, respectively. Chickens from Group D were vaccinated twice—at the first day and 7 wk old. Chickens from Group E were vaccinated twice—at the first day and 16 wk old. Chickens from Group F were vaccinated twice—at 7 and 16 wk old. Chickens from Group G were vaccinated 3 times, following the manufacturer's recommendation: at the first day, 7 and 16 wk old. Chickens from Group H remained unvaccinated. Five challenge trials numbered 1 to 5 were carried out at 8, 12, 16, 29, and 55 wk old, respectively. After challenge, chickens were sampled by cloacal swabbing and, after euthanasia, livers, ovaries, spleens, and cecal contents were cultured to isolate S. Enteritidis. Additionally, eggs were collected after challenge and cultured to isolate S. Enteritidis on egg shells (Trials 4 and 5). Protection against experimental infection with a virulent nalidixic acid resistant S. Enteritidis strain K285/94, was evaluated by measuring reduction of excretion, colonization, invasion into organs, eggshell contamination, and egg production. The live S. Enteritidis vaccine protected the hens by reducing S. Enteritidis excretion, isolation from organs, and egg contamination. Higher protection throughout laying period was afforded after administration of three vaccine doses during rearing period.
Se evaluó la presencia de Salmonella en 680 huevos frescos de gallina, provenientes de 4 granjas de Lima y 4 de Chincha y de los mercados de Ate-Vitarte, Surco y Villa El Salvador, se evaluó la cáscara y la parte interna del huevo, se comprobó la selectividad del agar Xilosa-Lisina-Tergitol4 (XLT4) en la recuperación y el aislamiento de especies del género Salmonella, con una significancia estadística p < 0,01, frente al agar Hecktoen. En el análisis de los huevos frescos de gallina no se encontró Salmonella ente rica serovar. Enteritidis, sin embargo se obtuvo Salmonella entérica serovar. Djugu y Salmonella entérica serovar. Mbandaka.
Abstract – This work refers to the appearance in Argentina in 1986 of pathogenic strains of Salmonella Enteritidis in broiler breeder farms in Argentina. A "new" disease is described in which the breeding birds generally have no obvious symptoms but their progeny of broilers have high mortality, non- uniform growth and dwarfism. At slaughter enteric and hepatic lesions, pericarditis, fibrin-purulent peritonitis are found. In 1 day-old chicks incomplete resorption of yolk sac is observed. The economic impact of this disease is detailed and compared its simultaneous appearance in many other parts of the world with serious consequences for public health. – Resumen – Este trabajo se refiere a la aparición en Argentina en 1986 de cepas patógenas de Salmonella Enteritidis en una granja de reproductores pesados en Argentina. Se describe una “nueva” enfermedad en la cual las aves reproductoras generalmente no tienen síntomas evidentes pero su progenie de pollos de engorde presenta elevada mortalidad con desuniformidad del lote y enanismo. A la faena se observan lesiones entéricas y hepáticas, pericarditis y peritonitis fibrino-purulentas. En pollitos BB se observa reabsorción incompleta del saco vitelino. Se detalla el impacto económico de esta enfermedad y se compara su aparición simultánea en otras partes del mundo con serias consecuencias para la salud pública.
Abstract – Production of paratyphoid in broilers by inoculation of Salmonella enterica subsp. enterica serovar Enteritidis. Four hundred broiler chicks between 1-9 days old were orally inoculated with 2 strains of the serovar Enteritidis isolated from avian paratyphoid outbreaks. Their clinical and mortality records were compared during 7-10 days post-inoculation with 1372 naturally infected chickens used as controls. Taking into account the age of animals and the strain used, the inoculated chicks were divided into 6 groups of 50 birds and one group of 100 birds. The controls were distributed according to age into 3 groups of similar numbers of birds. Some the inoculated chicks were treated during their first day of life with furazolidone in the balanced food. The mortality of the inoculated groups (16.8%) was significantly higher (p <0.001) than controls (2%). More birds died when inoculated with 10^9.01 (37%) than with 10^8.24 (17%). Significant differences (p<0.001) were found between mortality of chicks inoculated at 2 days of age (37%) and that of those infected at 7 or 9 days of age (6.9%). Furazolidone treated animals had significantly lower (p <0.01) mortality (11.5%) than those untreated (45.9%). In the birds that were observed until the 10th day post-inoculation, more (p <0.001) dwarf chickens were detected in inoculated flocks (12%) than in control ones (2.5%). Both strains produced similar mortality rates. – Resumen – Cuatrocientos pollitos parrilleros de 1 a 9 días de edad fueron inoculados oralmente con 2 cepas de la serovariedad Enteritidis aisladas de brotes de paratifosis aviaria. Sus registros clínicos y de mortandad se compararon durante 7-10 días post-inoculación con 1372 pollitos infectados naturalmente y utilizados como testigos. Considerando su edad y la cepa utilizada, los animales inoculados se dividieron en 6 grupos de 50 aves y 1 grupo de 100 aves. Los testigos se distribuyeron de acuerdo con su edad en 3 grupos de similar número de aves. Algunos pollos inoculados fueron tratados durante su primer día de vida con furazolidona en el alimento balanceado. La mortalidad de los grupos inoculados (16,8%) fue significativamente mayor (p<0,001) que la de los testigos (2%). Murieron más aves cuando se inocularon con 10^9,01 (37%) que con 10^8,24 (17%). Se hallaron diferencias significativas (p<0,001) entre la mortalidad de los pollitos inoculados a los 2 días de vida (37%) y aquellos infectados a los 7 ó 9 días de edad (6,9%). Los animales tratados con furazolidona tuvieron significativamente menor (p<0,01) mortalidad (11,5%) que los no medicados (45,9%). En las aves que se observaron hasta el 10° día post-inoculación se detectaron mayor (p<0,001) cantidad de aves enanas (12%) que en las testigos (2,5%). No se encontraron diferencias comparando la mortalidad producida por las dos cepas utilizadas.
Introducción: La detección de Salmonella sp se encuentra incluida dentro del programa de vigilancia epidemiológica en Colombia debido a su importancia en salud pública, siendo uno de los microorganismos más frecuentemente relacionados con enfermedades transmitidas por alimentos (ETA). Su transmisión se da principalmente a través del consumo de productos avícolas como el pollo o el huevo contaminados con la bacteria. Objetivo: El propósito del presente estudio fue determinar la presencia de Salmonella Enteritidis en hue-vos para consumo humano comercializados en la ciudad de Tunja (Colombia). Materiales y métodos: Se examinaron 230 huevos provenientes de cinco avícolas ubicadas en diferentes expendios de la ciudad de Tunja y de un vendedor independiente. Se aplicó el protocolo para la detección de Salmonella, establecido según la Norma Técnica Colombiana 4574, determinando también el serotipo de los aislados de Salmonella empleando antisueros somáticos e indivi-duales y el factor 46 del grupo D 2. Resultados: Se logró identificar Salmonella Enteritidis en cuatro huevos, lo que corresponde al 1,74% del total de las muestras. Adicionalmente, se recuperaron once especies bacterianas diferentes a Salmonella, provenientes de la cáscara, clara y la yema de los huevos examinados, entre los cuales se encontraron algunas especies bacterianas que pueden representar riesgo para la salud humana. Conclusión: La circulación de Salmonella Enteritidis en los huevos de gallina comercializados en la ciudad de Tunja, constituye en un riesgo para la salud del consumidor. Por tal motivo, la vigilancia de los productos elaborados a base de huevo es indispensable en la prevención de enfermedades generadas por este microorganismo.
Salmonella spp. is the main originator of human foodborne diseases worldwide and is mainly transmitted by food containing eggs. In Brazil, as a result of the lack of studies and data collection very little is known about the prevalence of Salmonella spp. in laying hen flocks and commercial table eggs. Consequently the present study was elaborated and aimed at generating data about Salmonella spp. in part of the Brazilian egg production chain. Eight flocks of day-old chicks, eight flocks of adult laying hens (four vaccinated with bacterin against Salmonella Enteritidis and four unvaccinated) and commercial table eggs from four supermarkets were examined. Salmonella spp. was isolated in 50 % of the newly hatched chicks, 25 % of the adult flocks and 1.5 % of egg samples examined. S. enterica subsp. enterica 4,12:r:-, S. Mbandaka, S. enterica subsp. enterica 6,7: z10:-, S. Enteritidis and S. Havana were the serovars isolated in birds. In commercial table-eggs S. Mbandaka, S. enterica subsp. enterica 6,7: z10:- and S. Braenderup were isolated. These results show that Salmonella spp. is present in laying hen flocks and consequently in eggs destined for human consumption. Probably, some of the Salmonella serovars are being introduced in egg farms by vertical via.
Salmonellosis affects humans more frequently than any other foodborne disease, and it causes severe economic losses in the poultry industry. A cross-sectional study was carried out to estimate the prevalence of Salmonella spp. in laying hen farms in the Tolima region of Colombia. Fifteen egg-laying hen farms were sampled, and a total of 589 samples were cultured to isolate Salmonella spp. A total of 14 isolates of Salmonella spp. were recovered from five farms, resulting in a prevalence of 33.33% (95%, confidence interval = 14%–53%) at the farm level. Salmonella spp. were recovered from eggshells (57.15%, n = 8), feed (28.57%, n = 4), and environmental samples (14.29%, n = 2). Farm practices, such as the milling of feed (odds ratio [OR] = 24) and the storage of eggs in the henhouses (OR = 11.25), in addition to the feed type (OR = 7.64) and the use of bamboo for construction of the facility (OR = 5.24), were identified as risk factors for Salmonella spp. The 14 isolates were identified as Salmonella Enteritidis (n = 6) and Salmonella Shannon (n = 8), and both serovars were resistant to a number of antibiotics. Pulsed-field gel electrophoresis presented three different XbaI macrorestriction patterns. The Salmonella Enteritidis isolates all presented a single pattern, whereas the Salmonella Shannon isolates were grouped into two distinct patterns. The results indicate that Salmonella spp. could be recovered from various sources at laying hen farms, and eggshell contamination is a particular concern.
Evaluate the sanitary quality of raw chicken sold in the urban area of the State of Merida, Venezuela and characterize the phenotype of isolated Samonella enterica strains.
Foodborne diseases and other enteric infections often occur as outbreaks and cause morbidity and mortality all over the world. In Perú, they represent a serious public health problem, and are caused by a great variety of infectious agents. For epidemiological research, a wide array of typification methods are used. One of the most important tools for the molecular subtyping of bacterial pathogens is the Pulsed Field Gel Electrophoresis (PFGE), which is a highly precise method that allows the discrimination between different bacterial isolates which are epidemiologically related. The Instituto Nacional de Salud del Perú (INS) is part of the WHO Global Foodborne Infections Network (WHO-GFN) and of the PulseNet Latin American and Caribbean Net (PN-AL & C), with whom it shares the genetic profiles of the isolated pathogenic strains, so that it is possible to compare de genotypes of similar strains found in different countries and to identify the occurrence of epidemic outbreaks in the region, strengthening the regional system of epidemiological surveillance and generating a rapid, coordinated response between the countries. We present the two last years´ experience including the advances in the use of these strategic tools that have allowed us to characterize genotype patterns implicated in foodborne diseases from isolates recovered in the laboratory network of Peru.
Salmonella enterica is frequently associated with outbreaks of human salmonellosis, and products of avian origin, such as eggs and chicken meat, are the main vehicles of its transmission. The present study describes the occurrence of different serovars of Salmonella enterica and phagotypes of S. enterica serovar Enteritidis in eggs destined for human consumption. Four thousand eggs obtained from commercial egg laying farms and one thousand discarded hatching eggs from broiler farms, which were acquired at farmers' markets and informal shops, were analyzed. Salmonella spp. was isolated from 52.0% of the discarded hatching eggs, in which the predominant serovar was Enteritidis (84.6%), and the predominant Salmonella Enteritidis phagotype (PT) was PT7 (26.9%). Salmonella spp. was not isolated from eggs obtained from commercial egg laying farms. The antimicrobial resistance profile showed that 23.1% (n = 6) of the SE strains were resistant to nalidixic acid. The results suggest that the consumption of discarded hatching eggs represents an important source of Salmonella transmission to humans.
Contamination of ISA BROWN layer hens by Salmonella spp. and serotyping of the isolated strains were performed in 30 farms. Salmonella detection was done from feces and cloaca swabs. Eggs produced in the farms contaminated by Salmonella spp. were analyzed by culturing the shell rinsing and egg yolk. Salmonella spp. was isolated in eight (23.0%) farms, but was not detected from eggs. S. Enteritidis, which is the most prevalent sorotype associated to human salmonelosis in Paraná State, was not isolated either from birds or eggs analyzed. The sorotypes isolated were Salmonella enterica subsp. enterica (0:3.10) (67.0%), Mbandaka (11.0%), Infantis (11.0%), and Newport (11.0%).
The emergence and spread of antimicrobial resistance among Salmonella serovars originating from food-producing animals and their immediate environment is a major public health problem, because Salmonella is one of the most common causes of human foodborne illness (1).…
During year 2011 two outbreaks of Salmonella infection captured media attention in the Metropolitan Area (MA) in Chile: one of typhoid fever associated to Salmonella serotype Typhi, and the other, of gastroenteritis related to Salmonella serotype Enteritidis, both with decreasing or stable rates in the previous years. The aim of this work is to analyze probable causes of their reemergence. Methods: Several government websites were searched looking for epidemiological data. Results: Typhoid fever rates have declined to current values of 1 case per 100.000 habitants, a decreased associated to improvements in the human development index. The typhoid outbreak was associated to a predominant clone within the MA. The only risk factor identified was consumption of raw vegetables acquired in open fairs, but without identifying a common source. Despite improvements in disease notification and molecular epidemiology capabilities, this outbreak is coincidental with a reduced number of food inspection visits in the MA, probably explained by the limited personnel available for this task. In the case of Salmonella Enteritidis, rates have increased twice since 1998 (5.3 to 10.7 per 100.000 habitants) with an important increase in the number of outbreaks linked to this agent (7 to 31 annual outbreaks) since year 2005. Persistence of this problem is probably associated to the low surveillance of poultry farms made by the Chilean state, to the absence of a cold chain during collection, distribution and selling of eggs, and to the lack of an educational program directed to the population. The recent regulation that bans home-made mayonnaise in restaurant or fast food stores is an important advance that requires further evaluation. Conclusions: The persistence and reemergence of different kind of Salmonellosis in Chile suggests chronic problems on the size and role of the Chilean state regarding food safety.
RESUMEN Se analiza la influencia de los diferentes modelos económicos sobre la utilización de los recursos naturales de Latinoamérica desde una perspectiva histórica, con un énfasis en los productos de exportación. En primer lugar, se aporta una breve mirada histórica al tema: cómo las políticas del modelo exportador y del modelo de substitución de importaciones e industrialización han influido en el crecimiento económico y la explotación de los recursos naturales. Enseguida, el nuevo modelo económico y sus efectos en el uso de los recursos naturales se describe a detalle y, finalmente, se presentan algunas observaciones sobre la crisis global actual y sus posibles implicaciones. Palabras clave: recursos naturales, Latinoamérica, modelos económicos, exportaciones no tradicionales.
Salmonella enterica is commonly acquired from contaminated food and is an important cause of illness worldwide. Interventions are needed to control Salmonella; subtyping Salmonella by serotyping is useful for targeting such interventions. We, therefore, analyzed the global distribution of the 15 most frequently identified serovars of Salmonella isolated from humans from 2001 to 2007 in laboratories from 37 countries that participated in World Health Organization Global Foodborne Infections Network and demonstrated serotyping proficiency in the Global Foodborne Infections Network External Quality Assurance System. In all regions throughout the study period, with the exception of the Oceania and North American regions, Salmonella serovars Enteritidis and Typhimurium ranked as the most common and second most common serovar, respectively. In the North American and Oceania (Australia and New Zealand) regions, Salmonella serovar Typhimurium was the most common serovar reported, and Salmonella serovar Enteritidis was the second most common serovar. During the study period, the proportion of Salmonella isolates reported from humans that were Salmonella serovar Enteritidis was 43.5% (range: 40.6% [2007] to 44.9% [2003]), and Salmonella serovar Typhimurium was 17.1% (range: 15% [2007] to 18.9% [2001]). Salmonella serovars Newport (mainly observed in Latin and North American and European countries), Infantis (dominating in all regions), Virchow (mainly observed in Asian, European, and Oceanic countries), Hadar (profound in European countries), and Agona (intense in Latin and North American and European countries) were also frequently isolated with an overall proportion of 3.5%, 1.8%, 1.5%, 1.5%, and 0.8%, respectively. There were large differences in the most commonly isolated serovars between regions, but lesser differences between countries within the same region. The results also highlight the complexity of the global epidemiology of Salmonella and the need and importance for improving monitoring data of those serovars of highest epidemiologic importance.
Salmonella enterica serovar Enteritidis (S. Enteritidis) is frequently associated with food-borne disease worldwide. Poultry-derived products are a major source. An
epidemic of human infection with S. Enteritidis occurred in Uruguay, and to evaluate the extent of poultry contamination, we conducted a nationwide survey over
2 years that included the analysis of sera from 5,751 birds and 12,400 eggs. Serological evidence of infection with Salmonella group O:9 was found in 24.4% of the birds. All positive sera were retested with a gm flagellum-based enzyme-linked immunosorbent
assay, and based on these results, the national prevalence of S. Enteritidis infection was estimated to be 6.3%. Salmonellae were recovered from 58 of 620 pools made up of 20 eggs each,
demonstrating a prevalence of at least 1 in every 214 eggs. Surprisingly, the majority of the isolates were not S. Enteritidis. Thirty-nine isolates were typed as S. Derby, 9 as S. Gallinarum, 8 as S. Enteritidis, and 2 as S. Panama. Despite the highest prevalence in eggs, S. Derby was not isolated from humans in the period of analysis, suggesting a low capacity to infect humans. Microarray-based
comparative genomic hybridization analysis of S. Derby and S. Enteritidis revealed more than 350 genetic differences. S. Derby lacked pathogenicity islands 13 and 14, the fimbrial lpf operon, and other regions encoding metabolic functions. Several of these regions are present not only in serovar Enteritidis
but also in all sequenced strains of S. Typhimurium, suggesting that these regions might be related to the capacity of Salmonella to cause food-borne disease.
This study was carried out to investigate the presence of Salmonella sp in flocks of white laying hens. In different farms, the transport boxes of twelve flocks were inspected at arrival for the presence of Salmonella. Four positive (A, B, L and M) and one negative (I) flocks were monitored at each four weeks using bacteriological examination of cecal fresh feces up to 52 weeks. Birds were also evaluated at 52 weeks, when 500 eggs were taken randomly, and at 76 weeks, after forced molt. Salmonella enterica serovar Enteritidis and S. enterica rough strain were isolated from the transport boxes of the four positive flocks (flocks A, B, L and M). Salmonella sp was not isolated from the transport boxes or from the feces after 76 weeks-old in flock I. Salmonella sp was isolated in the 1st, 11th, 34th, 42nd and 76th weeks from flock A; in the 1st, 4th, 11th and 76th weeks from flock B; in the first week and in the 17th to 52nd weeks from flock L; and in the 1st and 76th weeks from flock M. S. Enteritidis, S. enterica rough strain and Salmonella enterica serovar Infantis were isolated from the four positive flocks. Besides, Salmonella enterica serovar Javiana was isolated from flocks B and L, and Salmonella enterica serovar Mbandaka was isolated from flock L. Eggs produced by flock A and by flock L were contaminated with S. Enteritidis and S. enterica rough strain. According to these results, Salmonella-infected flocks may produce contaminated eggs.
Molecular and phenotyping techniques were applied to study Salmonella enterica serovar Enteritidis strains both from human cases of infection and of avian origin isolated in Uruguay from 1995 to 2002. A group of 62 isolates was subjected to random amplified polymorphic DNA (RAPD) assay and analysis of antibiotic resistance patterns. Twenty-one of these strains were further characterized by phage typing and analysis of their protein expression profiles. RAPD fingerprinting with five different primers discriminated 10 different genetic profiles. Of the 62 strains tested, 48 had a single major genetic profile, whereas the other nine profiles were evenly distributed among the other strains. The genetic diversity was greater among strains of animal origin than among isolates of human origin. Comparative examination of the results obtained by RAPD analysis and phenotypic analysis and by strain source provided evidence of the reliable discriminatory power of RAPD analysis in our study. Six avian isolates with antibiotic resistance were detected: two were nalidixic acid resistant and four had a particular beta-lactam resistance pattern. The last four isolates all had the same unusual phage type (phage type 4b); however, RAPD analysis differentiated them into two groups. Two isolates with unique RAPD profiles were recovered from distinct human cases, suggesting that the technique differentiates unrelated strains. Overall, the results show the existence of a predominant genetic type that is present in poultry and that is transmitted to humans. There are also several other genotypes, but only a few of them could be recovered from human sources, suggesting the existence of different pathogenic traits among strains circulating in the country.
A small (8.2-kb) ColE1 plasmid encoding TEM-144 (a new β-lactamase with a ceftazidimase profile) was sequenced by a gene-walking
strategy. The blaTEM allele was carried on a Tn2 element, disrupting a Rom protein gene. TEM-144 differs from TEM-1 by two mutations (R164C and E240K) and from the ceftazidime-hydrolyzing
TEM-91 by one mutation (T182M).
To determine the occurrence of antimicrobial resistance genes and role of integrons among 135 antimicrobial-resistant Salmonella enterica from Brazil.
The presence of antimicrobial resistance genes, class 1 and 2 integrons and gene cassettes was analysed by PCR and sequencing. The genetic location of class 1 integrons was determined in 25 isolates by hybridization and plasmid transfer experiments.
Fifty-five of the isolates were positive for class 1 integrons. Integron-positive isolates represented 17 different serovars and were mainly from human (n=28) and animal (n=13) sources. The gene cassette arrangements could be determined in 51 of the positive isolates, which harboured one [dfrA22, aadA1 or orf3 (putative trimethoprim resistance)], two [aadA1-dfrA1, aac(6')-Ib-orf1 (unknown function) or aacA4-aadA1], three [dfrA15b-cmlA4-aadA2, orf2 (unknown function)-dfrA5-orfD] or four [orf4-aacA4-blaOXA-30 (interrupted by an IS1 element)-aadA1] cassettes in their variable region. Only one isolate harboured a class 2 integron with the gene cassette array dfrA1-sat-aadA1. Several integron unrelated resistance genes were also detected in the isolates. Sulphonamide resistance was primarily mediated by sul2 and sul3, tetracycline resistance by tet(B) and tet(A), chloramphenicol resistance by catA1, streptomycin resistance by strA and ampicillin resistance by blaTEM. blaCTX and blaCMY-2 were found in cephalosporin-resistant isolates. Mating and hybridization experiments demonstrated that a high-molecular-weight plasmid mediated the gene transfer of integrons and additional resistance determinants.
The present study revealed that integron-mediated resistance genes contributed to the multiresistance phenotype observed in the isolates, but most resistance genes were located outside the integron structure, as independent genes. However, they might be located on the same conjugative plasmid.
A severe outbreak of salmonellosis in commercial brown table egg layers first occurred in Colombia in 2006. From 2008 to 2012, 35 samples collected from commercial layers farms in the states of Cundinamarca, Santander, Bolivar, and San Andres, were positive for Salmonella enterica. Salmonella was isolated from liver and spleen (71.42%), pools of organs (liver, spleen, and ovarian follicles; 25.71%), and drag swabs (2.85%). Serotype was assigned using single nucleotide polymorphisms or DNA microarray hybridization. Sixteen strains of Salmonella Enteritidis, and 13 of Salmonella Gallinarum were identified. Seven strains yielded three unique sequences, and they were designated as UN0038, UN0052, and UN0054 by intergenic sequence ribotyping. These strains were later identified as Salmonella serotypes Isangi, Braenderup, and Yoruba, respectively, by DNA microarray hybridization. The discovery that a common human pathogen (Salmonella Enteritidis) was coisolated from farms with an avian pathogen (Salmonella Gallinarum) in similar commercial brown layer hens and in different regions indicates that it is important to investigate the dynamics of Salmonella infection and determine the serotypes circulating within the same ecologic niche.
This study was aimed to determine the prevalence of Salmonella spp. in foods of animal origin sold at retail stores over the period 2005–2011 in San Luis, Argentina. Characterization of isolates was performed by biochemical and serological tests, antimicrobial susceptibility assays, detection of invA invasion gene by PCR and comparison of genomic profiles by XbaI DNA restriction and PFGE. Twenty seven Salmonella strains were detected in 27 (6.32%) of 427 samples of foods analysed. Sixteen S. Enteritidis and one S. Montevideo strains from chicken meat (17 positive samples/115 total samples), six S. Anatum strains from pork sausages (6/90), two S. Typhimurium strains from liquid egg (2/60) and two S. Montevideo strains from chicken giblets (2/62) were isolated. No Salmonella strains were recovered from chicken carcasses (0/100). Salmonella strains were susceptible to antimicrobials commonly used for clinical treatment. All isolates carried the invA gene. DNA restriction and PFGE analysis revealed similar genomic profiles within each Salmonella serovar regardless of the food type, sampling year, or retail store where samples were purchased, suggesting the possibility of circulation and transmission of clones of limited diversity in our region.
Ten Salmonella enterica serovar Typhimurium isolates producing CTX-M-2 extended-spectrum beta-lactamase were identified from clinical and poultry sources in two distant cities in Brazil between 2003 and 2004. They included two isolates from pediatric patients and eight isolates from poultry or its environment. All isolates exhibited coresistance to non-beta-lactam antimicrobials including tetracycline and trimethoprim/sulfamethoxazole. The CTX-M-2 gene was located on transferable plasmids with sizes between 90 and 170 kb that also carried other resistance determinants in some isolates. By pulsed-field gel electrophoresis, the genetic similarity of the isolates including clinical and poultry ones ranged from 89% to 100%.
To study the evolution of antibiotic resistance in isolates of Salmonella enterica subspecies enterica serovar Typhimurium (Salmonella Typhimurium) obtained in Uruguay between the years 1976 and 2000, and to determine the incidence of class 1 and 2 integrons in the multi-resistant isolates.
We studied 258 strains of Salmonella Typhimurium from various sources, isolated between 1976 and 2000. We determined the evolution of antibiotic resistance and the distribution of class 1 and 2 integrons in all isolates by means of disk diffusion assays and PCR.
During the period 1989-2000 resistance to streptomycin was 56.8%, tetracycline 13.6%, sulfonamides 11.2%, and ampicillin 7.2%. Resistance to gentamicin, kanamycin, chloramphenicol, and nalidixic acid were lower than 5%; no resistance was detected to fluoroquinolones, oxyiminocephalosporins, and amikacin. These results show a dramatic decrease with respect to values found in the period 1976-1988. In this period, resistance to streptomycin was 63.2%, tetracycline 36.8%, sulfonamides 32.3%, and ampicillin 27.8%. Throughout the two periods, 29 multi-resistant Salmonella Typhimurium strains were isolated harboring some class of integron: 15 strains had only intI2, 11 strains presented both intI1 and intI2, and three isolates only intI1.
Our results show a marked decrease in resistance throughout these years, along with a correlation between resistance to different antibiotics and the presence of integrons.
A significant increase in the number of isolations of Salmonella enteritidis has been observed in Argentina since 1986. Outbreaks of foodborne diseases in humans were associated with the consumption of raw or undercooked hens' eggs. Between 1986 and the first 6 months of 1993 there were 150 outbreaks reported, affecting more than 6000 persons. A total of 71.3% of these outbreaks were confirmed by stool cultures, and 47.3% by bacteriological study of the food implicated in the outbreak. A permanent surveillance of salmonellosis is imperative, taking into account the persistence of Salmonella enteritidis isolations in sporadic cases and in new outbreaks.
beta-Lactamases with pIs of 5.4 and 8.1 were detected by hydrolysis of ampicillin and ceftriaxone respectively among cefotaxime resistant serovars of Salmonella spp. suggesting TEM-1 and an unidentified extended spectrum beta-lactamase have spread throughout these strains in Argentina.
Since 1994 an extensive epidemic of infections with Salmonella enteritidis (S. enteritidis) has affected Chile. In order to understand the diversity of infective sources, the possible origin of the epidemic, and the epidemiological relationships between clinical, food, and poultry isolates, we carried out phage typing of three groups of samples: 1) 310 S. enteritidis clinical samples collected between 1975 and 1996, 2) 47 food isolates obtained during S. enteritidis outbreaks, and 3) 27 strains isolated in surveillance studies of poultry-raising establishments. With the clinical samples, a total of 13 phage types were identified, 2 isolates could not be typed, and 1 was considered atypical. The phage types that were identified most frequently were 1 (56.8%) and 4 (31.3%), trailed by type 8 (4.8%) and type 28 (1.9%). Over time and in different regions of the country there were major changes in the distribution of the phage types. In the first years of collection the only phage types registered were 8 and 28, which disappeared around 1980 and then began reappearing sporadically in 1996. With the gradual S. enteritidis expansion that started in 1988, in the central and southern areas of the country phage type 4 began to appear; that type had not been found before in Chile. In 1991 in the northern area of the country phage type 1 began to predominate; it was another type that had not been reported before in Chile. In the food isolates the only phage types identified were 1 and 4, which were also the most common in the poultry isolates. Phage typing of S. enteritidis has proved to be useful in guiding the epidemiological analysis of the infections caused by this pathogen.
Salmonella enteritidis (SE) is a frequent cause of diarrhea, and is transmitted mainly by SE contaminated eggs or poultry meat. The frequency of SE contaminated eggs or chicken meat and the risk for acquiring this pathogen is unknown in Chile.
To measure SE contamination in eggs poultry meat and entrails offered in retail markets in the Metropolitan Area during two consecutive years (1998-1999).
Samples were placed in sterile bags and transported to the laboratory before 4 hours at 4 degrees C. Microbiologic detection was done using a standard procedure and an immunodetection assay.
SE was found in one of 1081 egg samples (0.09%). The contaminated sample was offered in a supermarket under their own commercial name. Six percent of 1154 poultry meat samples were contaminated by SE and 2.3% by other Salmonella serotypes. Entrails had even higher rates with 10.2% of 370 samples harboring SE and 2.7% other serotypes. Total Salmonella sp. isolates and SE isolates declined during 1999. Nine SE phagotypes were identified, predominating types 4 and 7.
Eggs and other avian products are contaminated by different SE phagotypes and other Salmonella serotypes, implicating a risk for the consumers (Rev Méd Chile 2000; 128: 1075-83).
Antimicrobial resistance was investigated in 91 Salmonella enteritidis isolates from broiler carcasses, food, human and poultry-related samples originated from South of Brazil. A great proportion of resistant strains was found, 90.1% showing resistance to at least one antimicrobial drug. There was a high resistance to sulfonamides (75.8%) and nitrofurantoin (52.8%). Lower levels of resistance were found for tetracycline (15.4%), streptomycin (7.7%), nalidixic acid (7.7%), gentamicin (5.5%), norfloxacin (3.3%), trimethoprim (3.3%), cefalotin (2.2%), ampicillin (1.1%), and chloramphenicol (1.1%). Resistance to ciprofloxacin was not detected. A total of 51.6% of S. enteritidis strains were multiresistant (resistance to two or more antimicrobial agents) and 18 resistance patterns were found. The highest resistance was found in strains isolated from poultry-related samples, where all strains were resistant to at least one antimicrobial agent. No predominant resistance pattern was related to phage type in our isolates. The high number of antimicrobial resistant S. enteritidis found in Southern Brazil indicates the need for the prudent drugs uses to diminish the development and spread of antimicrobial resistance.
The antimicrobial susceptibility of 94 Salmonella strains isolated from different poultry farms in Chile (broiler and laggin hens) were analyzed by the dilution plates method. Thirty-nine of them were resistant to flumequine, nalidixic acid and oxolinic acid with MIC values higher than 64 microg/ml. These quinolone resistant strains were analyzed in order to determine the presence of mutations in the QRDR region of gyrA gene by AS-PCR-RFLP analysis. 51.3% of the strains showed mutations at codon Ser 83 and 41.0% showed mutations at codon Asp 87. No mutations were observed on codon Gly 81. These mutations were confirmed by sequenciation of one representative strain from different RFLP pattern. Likewise, no double mutations were observed. Over 90% of the quinolone resistant strains presented mutations at the QRDR region of the gyrA gene. Three phenotypically resistant strains did not show any mutations on the QRDR region of gyrA gene. However, other molecular resistant mechanism could be involve. This is the first study that demonstrate the emergency of quinolone and fluoroquinolone resistance in Chilean Salmonella strains isolated from poultry thus indicating the requirement of monitoring programmes in veterinary medicine.
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