Suchergebnisse

Los alimentos como la carne molida de vacuno, queso, jamón y lechuga son de alta demanda de consumo por la población y son susceptibles de contaminación. Así mismo, las aguas de los ríos son usadas por pobladores de las riberas. En nuestro medio, no contamos con reportes sobre estudios de vigilancia de E. coli O157:H7 en muestras de aguas del río Rímac este, ni en alimentos en los mercados de Lima. Para la evaluación de alimentos se procedió como lo describe Feng & Weagant (2002) y para aguas se utilizó 150 mL de la muestra con 150 mL de TSBm doble concentrado e incubado a 37ºC por 18 h y transferido a agar Mac Conkey e incubado a 37ºC por 24 h. Se seleccionaron 5 colonias lactosa positiva por muestra e identificadas como E. coli, así como su incapacidad para utilizar el sorbitol y la determinación del antígeno somático O157 y el flagelar H7, confirmándose E. coli O157:H7. De las 309 muestras de alimentos, 82 lechugas, 76 quesos, 76 jamón y 75 de carne molida, procesadas, 187 resultaron positivas para E. coli (60,5%), correspondiendo a 47 provenientes de lechugas, a 60 de queso fresco, a 48 de jamón y a 32 de carne molida; mientras que de las 75 muestras de aguas de río procesadas, 36 resultaron positivas para E. coli (48%). De 223 cultivos de E.coli evaluados, cinco (5) cultivos fueron positivos para E. coli O157:H7, correspondiendo a 2 de lechugas (2,4%) y 3 de carne molida (4%). No se detectó E. coli O157:H7 en muestras de aguas, jamón y queso. La lechuga puede representar un alimento de alto riesgo en la transmisión de E. coli O157:H7 al hombre, seguido de la carne, por contaminación cruzada o por mal cocimiento.Palabras claves: E. coli O157:H7, alimentos, aguas

We identified the mucus-activatable Shiga toxin genotype stx2d in the most common hemolytic uremic syndrome-associated Escherichia coli serotype, O157:H7. stx2d was detected in a strain isolated from a 2-year-old boy with bloody diarrhea in Spain, and whole-genome sequencing was used to confirm and fully characterize the strain. ; This work was supported by grants MPY-1042/14 and PI14CIII/00051 from "Fondo de Investigaciones Sanitarias" from the Spanish Ministry of Economy and Competitiveness and S2013/ABI-2747 from the Madrid Regional Government. S.S. performed this work while under a research contract from the Miguel Servet program from "Fondo de Investigaciones Sanitarias" from the Spanish Ministry of Economy and Competitiveness (CP13/00237). ; Sí

Shiga‐toxin producing Escherichia coli (STEC) strains may cause human infections ranging from simple diarrhea to Haemolytic Uremic Syndrome (HUS). The five main pathogenic serotypes of STEC (MPS‐STEC) identified thus far in Europe are O157:H7, O26:H11, O103:H2, O111:H8, and O145:H28. Because STEC strains can survive or grow during cheese making, particularly in soft cheeses, a stochastic quantitative microbial risk assessment model was developed to assess the risk of HUS associated with the five MPS‐STEC in raw milk soft cheeses. A baseline scenario represents a theoretical worst‐case scenario where no intervention was considered throughout the farm‐to‐fork continuum. The risk level assessed with this baseline scenario is the risk‐based level. The impact of seven preharvest scenarios (vaccines, probiotic, milk farm sorting) on the risk‐based level was expressed in terms of risk reduction. Impact of the preharvest intervention ranges from 76% to 98% of risk reduction with highest values predicted with scenarios combining a decrease of the number of cow shedding STEC and of the STEC concentration in feces. The impact of postharvest interventions on the risk‐based level was also tested by applying five microbiological criteria (MC) at the end of ripening. The five MCs differ in terms of sample size, the number of samples that may yield a value larger than the microbiological limit, and the analysis methods. The risk reduction predicted varies from 25% to 96% by applying MCs without preharvest interventions and from 1% to 96% with combination of pre‐ and postharvest interventions.

In 1996, an outbreak of E. coli O157:H7‐associated illness occurred in an elementary school in Japan. This outbreak has been studied in unusual detail, making this an important case for quantitative risk assessment. The availability of stored samples of the contaminated food allowed reliable estimation of exposure to the pathogens. Collection of fecal samples allowed assessment of the numbers infected, including asymptomatic cases. Comparison to other published dose‐response studies for E. coli O157:H7 show that the strain that caused the outbreak studied here must have been considerably more infectious. We use this well‐documented incident as an example to demonstrate how such information on the response to a single dose can be used for dose‐response assessment. In particular, we demonstrate how the high infectivity limits the uncertainty in the low‐dose region.