Seasonal effect on Salmonella, Shiga toxin-producing E. coli O157:H7 and non-O157 in the beef industry in Colombia, South America.

This research investigated the variations in the occurrence of Salmonella, STEC O157:H7 and non-O157 in the beef production chain in Colombia affected by seasons, hypothesizing that pathogen prevalence will be highest in the rainy season owing to soil moisture promoting bacteria multiplication and transfer between animals. To test this hypothesis, samples were obtained from five abattoirs, which represent 50% of the beef production in this country. A total of 1017 samples were collected, from which 606 were bovine feces, 206 were hide swabs, and 205 corresponded to carcass post-intervention. From the 1017 samples, 49.9% (n = 507) were collected during dry season, while 50.1% (n = 510) during rainy season. All samples (n = 1017) underwent screening for E. coli O157:H7 and Salmonella, while only a proportion of fecal samples (n = 339) were screened for the big six STEC serogroups and their virulence markers. The effect of season, age of animal and sex of animal were correlated with the prevalence results. A total of 84.7% of fecal samples carried virulence genes associated to STEC (stx or eae), suggesting that testing and control should be increased for the big-six STEC compared to E. coli O157:H7. Pathogen prevalence in feces was found to be 8.3%, 5.0%, and 51.0% for Salmonella, E. coli O157:H7 and STEC non-O157, respectively. Hides had a prevalence of 15.0% and 6.8% of Salmonella and E. coli O157:H7, respectively. Carcasses post-intervention were found to have 4.4% and 2.5% prevalence of Salmonella and E. coli O157:H7, respectively. A seasonal effect was found for fecal samples. E. coli O157 and non-O157 STEC shedding were significantly higher (P ≤ 0.05) during rainy season compared to dry season. In contrast, hides and carcasses were more likely to present lower incidence of pathogens during rainy months compared to dry season; however, it was significant only for Salmonella on carcasses with estimated odds of detection almost six times higher in the dry season relative to the rainy season (OR = 5.90, 95% CI 1.18-29.57).

Assessment of a multiplex detection method for Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes in cow milk / Determinación de un método de detección múltiple para Salmonella enterica, Escherichia coli O157:H7 y Listeria monocytogenes en leche de vaca / Determinação de um método de detecção múltipla para Salmonella enterica, Escherichia coli O157:H7 e Listeria monocytogenes em leite de vaca

Abstract Raw cow milk is considered one of the most important vehicles for pathogenic bacteria like Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes. These three bacteria are responsible for foodborne diseases. Routine microbiological methods to detect these microorganisms in cow milk can be complicated and time consuming. The aim of this work was to evaluate a method to simultaneously detect Salmonella spp., Escherichia coli O157:H7, and Listeria monocytogenes in experimentally contaminated cow milk. The assessed method combined a standard microbiological culture step, using a pre-enrichment medium that favors the growth of the three focal microorganisms: SEL broth, followed by a single PCR assay. A total of 43 interference bacterial strains were used to evaluate the method's specificity. The detection rate for the microbiological method with standard culture media was 10 UFC/mL, and that of the PCR detection, following pre-enrichment in SEL broth, was 10 UFC/mL for S. enterica and L. monocytogenes and between 1 and 5 UFC/mL for E. coli O157:H7. The PCR method showed specificity for the reference strains. Simultaneous detection by multiple PCR using SEL broth was successful for the detection of S. enterica, E. coli O157:H7, and L. monocytogenes in samples of experimentally contaminated cow milk, featuring both a high detection rate and a high specificity. This approach promises to be a feasible routine procedure when testing milk samples in industry and public health control setups.

Resumen La leche cruda de vaca se considera uno de los vehículos más importantes de bacterias patógenas como Salmonella spp., Escherichia coli O157:H7 y Listeria monocytogenes. Estas tres bacterias son responsables de enfermedades transmitidas por alimentos. Los métodos microbiológicos de rutina para detectar estos microorganismos en leche cruda de vaca pueden ser complicados y requerir mucho tiempo. El objetivo de este trabajo fue evaluar un método para detectar simultáneamente Salmonella spp., Escherichia coli O157:H7 y Listeria monocytogenes en leche de vaca contaminada experimentalmente. El método utilizado combinó una etapa de pre-enriquecimiento con cultivo microbiológico estándar utilizando un medio que favorece el crecimiento de los tres microrganismos focales (caldo SEL) seguido de un único ensayo de PCR. Se utilizaron 43 cepas de microorganismos de interferencia para evaluar la especificidad del método. La tasa de detección para el método de cultivo microbiológico estándar fue de 10 UFC/mL, y la de detección por PCR, después de pre-enriquecimiento en caldo SEL, fue de 10 UFC/mL para S. enterica y L. monocytogenes y entre 1 y 5 UFC/ mL para E. coli O157:H7. El método PCR mostró especificidad para las cepas de referencia. La detección simultánea por PCR múltiple, luego de pre-enriquecimiento en caldo SEL fue exitosa para la detección de S. enterica, E. coli O157:H7 y L. monocytogenes en muestras de leche de vaca contaminada experimentalmente, mostrando tanto una alta tasa de detección como una alta especificidad. Esta aproximación promete ser un procedimiento de rutina factible cuando se analizan muestras de leche en la industria y en actividades de control de salud pública.

Resumo O leite de vaca cru é considerado um dos mais importantes veículos para bactéricas patogênicas como Salmonella spp., Escherichia coli O157:H7 e Listeria monocytogenes. Estas três bactérias são responsáveis por enfermidades transmitidas por alimentos. Os métodos microbiológicos de rotina para detectar estes micro-organismos em leite de vaca cru podem ser complicados e demandantes de tempo. O objetivo de este trabalho foi avaliar um método para detectar simultaneamente Salmonella spp., Escherichia coli O157:H7 e Listeria monocytogenes em leite de vaca contaminado experimentalmente. O método utilizado combinou uma etapa de pré- enriquecimento com cultura microbiológica padrão utilizando um meio que favorece o crescimento dos três micro-organismos focais (caldo SEL). Utilizaram-se 43 cepas de micro-organismos de interferência para avaliar a especificidade do método. A taxa de detecção para o método de cultura microbiológica padrão foi de 10 UFC/mL, e a de detecção por PCR, posteriormente ao pré-enriquecimento em caldo SEL, foi de 10 UFC/mL para S. enterica e L. monocytogenes e entre 1 e 5 UFC/mL para E. coli O157:H7. O método por PCR mostrou especificidade para as cepas de referência. A detecção simultânea por PCR múltiplex, logo do pré-enriquecimento em caldo SEL, foi exitosa para a detecção de S. entérica, E. coli O157:H7 e L. monocytogenes em amostras de leite de vaca contaminado experimentalmente, demostrando tanto uma alta taxa de detecção como uma alta especificidade. Esta aproximação promete ser um procedimento de rotina viável quando se analisam amostras de leite na indústria e nas atividades de controle de saúde pública.

Brotes por Salmonella spp., Staphylococcus aureus y Listeria monocytogenes asociados al consumo de pollo / Outbreaks of Salmonella spp., Staphylococcus aureus and Listeria monocytogenes associated with poultry consumption. Systematic review.

Introducción. Las enfermedades transmitidas por alimentos son un serio problema de salud pública y, el pollo, uno de los alimentos asociados con ellas. Objetivo. Determinar la distribución y frecuencia de brotes alimentarios asociados al consumo de pollo contaminado por Salmonella spp., Listeria monocytogenes y Staphylococus aureus, mediante una revisión sistemática de la literatura científica. Materiales y métodos. Se buscaron los estudios de brotes asociados a Salmonella spp., S. aureus y L. monocytogenes, en las bases de datos Medline, Pubmed, Science Direct,SciELO,Librería Cochrane (CCRT),Biblioteca Virtual en Salud (BVS), Highwire,HINARI y MedicLatina. Se obtuvieron los datos para el cálculo de odds ratios (OR) mediante la elaboración de tablas de contingencia en el programa RevMan5™. Resultados. Siete artículos cumplieron con los criterios de inclusión y no se encontraron reportes de L. monocytogenes. El OR global fue de 3,01 (IC95% 2,37-3,81), lo que se interpreta como una asociación significativa entre el consumo de pollo contaminado y la infección alimentaria. Se presentó heterogeneidad en los estudios incluidos (p=0,03), por lo que fue necesario un análisis por subgrupos de microorganismos; para el caso de Salmonella spp., el OR fue de 2,67 (IC95% 2,09-3,41). No se hizo análisis para S. aureus por reportarse un solo artículo. Conclusiones. Se encontró un OR de 2,61, lo que indica que hay una fuerte asociación entre el consumo de pollo y la adquisición de salmonelosis. El principal factor de riesgo para adquirir salmonelosis es el consumo de pollo de asadero en los restaurantes.

Introduction. Food borne diseases are a serious public health problem. Poultry are often associated with these outbreaks. Objective. A systematic review of the literature is provided concerning the distribution and frequency of food borne outbreaks associated with consumption of chicken contaminated with Salmonella spp., Listeria monocytogenes and Staphylococcus aureus. Materials and methods. The search for studies of outbreaks associated with Salmonella, S. aureus and L. monocytogenes was conducted in Medline, Pubmed, Science Direct, Scielo, Cochrane Library (CCRT), Virtual Health Library (VHL), Highwire, HINARI and MedicLatina. Data were obtained for the calculation of odds ratio (OR) by preparing contingency tables using the RevMan5 program. Results. Seven articles met the inclusion criteria; however, no reports of L. monocytogenes were obtained. The overall OR was 3.01 (95% CI: 2.37, 3.81); this was interpreted as a significant association between the consumption of contaminated chicken and food poisoning. In the included studies heterogeneity (p= 0.03) was presented, so it took a subgroup analysis of microorganisms, in the case of Salmonella OR was 2.67 (95% CI: 2.09 -3.41). No analysis was made for S. aureus reported a single article. Conclusions. The OR indicated a strong association between chicken consumption and acquisition of salmonellosis. The main risk factor for acquiring salmonellosis is the consumption of chicken from grill restaurants.

[Outbreaks of Salmonella spp., Staphylococcus aureus and Listeria monocytogenes associated with poultry consumption. Systematic review]. / Brotes por Salmonella spp., Staphylococcus aureus y Listeria monocytogenes asociados al consumo de pollo.

INTRODUCTION: Food borne diseases are a serious public health problem. Poultry are often associated with these outbreaks. OBJECTIVE: A systematic review of the literature is provided concerning the distribution and frequency of food borne outbreaks associated with consumption of chicken contaminated with Salmonella spp., Listeria monocytogenes and Staphylococcus aureus. MATERIALS AND METHODS: The search for studies of outbreaks associated with Salmonella, S. aureus and L. monocytogenes was conducted in Medline, PubMed, Science Direct, Scielo, Cochrane Library (CCRT), Virtual Health Library (VHL), Highwire, HINARI and MedicLatina. Data were obtained for the calculation of odds ratio (OR) by preparing contingency tables using the RevMan5 program. RESULTS: Seven articles met the inclusion criteria; however, no reports of L. monocytogenes were obtained. The overall OR was 3.01 (95% CI: 2.37, 3.81); this was interpreted as a significant association between the consumption of contaminated chicken and food poisoning. In the included studies heterogeneity (p= 0.03) was presented, so it took a subgroup analysis of microorganisms, in the case of Salmonella OR was 2.67 (95% CI: 2.09 -3.41). No analysis was made for S. aureus reported a single article. CONCLUSIONS: The OR indicated a strong association between chicken consumption and acquisition of salmonellosis. The main risk factor for acquiring salmonellosis is the consumption of chicken from grill restaurants.

DETERMINACIÓN DE Salmonella Typhimurium EN COMPOST INOCULADO ARTIFICIALMENTE EMPLEADO EN UN CULTIVO DE LECHUGA / Salmonella Typhimurium determination in compost artificially inoculated in a lettuce crop

Salmonella enterica serovariedad Typhimurium, se ha asociado a brotes por el consumo de frutas y vegetales contaminadas a partir de agua de riego, manipuladores, bioabono y suelo. En esta investigación se inoculó artificialmente un bioabono aplicado a un cultivo de lechuga para determinar la capacidad de transferencia a las plantas, así como establecer el efecto del uso de cubiertas de polietileno en la protección del cultivo frente a este patógeno. Para ello, se utilizaron plántulas de lechuga de ocho semanas y se establecieron cuatro tratamientos y dos controles: T1 y T2, con y sin cubierta de polietileno respectivamente, contenían una concentración de Salmonella enterica Serovariedad Typhimurium ATCC 13176 inoculada en el compost en concentración de 0,04 mo/g, T3 y T4 con y sin cubierta de polietileno respectivamente con 100 mo/g de compost y finalmente C1 y C2 con y sin cubierta pero sin inoculación. El seguimiento del microorganismo en suelo se realizó durante las ocho semanas del cultivo, mediante la técnica de NMP/4 g (EPA, 2006) al cabo de este tiempo se evaluó el total de plantas cultivadas mediante la misma técnica. Se determinó que Salmonella enterica serovariedad Typhimurium ATCC 13176 se transmite a la lechuga, a partir del bioabono contaminado (OR=2,53) sin importar la concentración inicial del microorganismo en el bioabono; así mismo se encontró que existe asociación entre la contaminación y la condición de cubierta del cultivo (p=0,002). Por otra parte, al analizar las raíces no se encontró asociación de transmisión.

Salmonella enterica serovariedad Typhimurium, has been associated with outbreaks because of the ingestion of fruits and vegetables and those outbreaks have been related due to contamination sources like irrigation water, farm workers influence and the soil itself. In this investigation it was artificially inoculated in a compost and later applied to a lettuce crop, in order to determine the transfer capacity of this microorganism to the plants, as well as to establish if the polyethylene cover protected the crop. In this study, four treatments were made with two controls, T1 and T2 - with and without polyethylene cover - these treatments and controls were inoculated with Salmonella enterica Serovariedad Typhimurium ATCC 13176 0,04 mo/g de compost, T3 y T4 - with and without polyethylene cover - each one with 100 mo/g de compost, and finally C1 and C2 - with and without polyethylene cover -, but without inoculation. At 8 weeks the microorganism was determine by the MPN/4g technique (EPA, 2006). Salmonella enterica serovariedad Typhimurium ATCC 13176 is capable to transfer itself to the lettuce, through the contaminated compost (OR=2.53) regardless of microorganism concentration in the compost, and there was an association between the contamination and the crop cover condition (p=0.002). The analysis of the roots and the irrigation water, demonstrated that it does not exist any transference association.