RESUMEN
Foodborne Salmonella spp. is a leading cause of foodborne illness in the United States each year. Traditionally, most cases of salmonellosis were thought to originate from meat and poultry products. However, an increasing number of salmonellosis outbreaks are occurring as a result of contaminated produce. Several produce items specifically have been identified in outbreaks, and the ability of Salmonella to attach or internalize into vegetables and fruits may be factors that make these produce items more likely to be sources of Salmonella. In addition, environmental factors including contaminated water sources used to irrigate and wash produce crops have been implicated in a large number of outbreaks. Salmonella is carried by both domesticated and wild animals and can contaminate freshwater by direct or indirect contact. In some cases, direct contact of produce or seeds with contaminated manure or animal wastes can lead to contaminated crops. This review examines outbreaks of Salmonella due to contaminated produce, the potential sources of Salmonella, and possible control measures to prevent contamination of produce.
Asunto(s)
Brotes de Enfermedades , Frutas/microbiología , Infecciones por Salmonella/epidemiología , Infecciones por Salmonella/prevención & control , Verduras/microbiología , Agricultura/métodos , Animales , Productos Agrícolas/microbiología , Cucurbitaceae/microbiología , Reservorios de Enfermedades/microbiología , Manipulación de Alimentos , Embalaje de Alimentos , Humanos , Solanum lycopersicum/microbiología , Mangifera/microbiología , Estiércol/microbiología , Plantones/microbiología , Estados Unidos/epidemiología , Microbiología del AguaRESUMEN
Many fruits and vegetables are irrigated with water from rivers, lakes and even wastewater systems. Irrigation may be a route for the introduction of Salmonella. Our objectives in this study were to determine survivability and virulence expression in a strain of Salmonella typhimurium when exposed to environmental water sources. Virulence expression was measured using a beta-galactosidase assay on a hilA:lacZY fusion strain of S. typhimurium. Water samples for environmental impact studies were taken from a local pond and specific sites along the Rio Grande River, which serves as a source of irrigation water in southern Texas. There was a significant difference (p<0.05) of virulence expression among the water sites. Certain regions along the Rio Grande River yielded greater amounts of beta-galactosidase activity than others. All sites yielded at least a two-fold greater virulence response than S. typhimurium grown in brain heart infusion. Salmonella survivors were enumerated as colony forming units (CFU)/ml as plated on a selective medium for the duration of 1 week and beta-galactosidase assays were performed to determine a possible correlation between culturable cells and virulence gene expression. Bacterial cells remained viable but decreased after 7 days incubation. In conclusion, water sampled at specific locations and at different times water samples exhibited differences in virulence expression in S. typhimurium.
Asunto(s)
Contaminación de Alimentos , Regulación Bacteriana de la Expresión Génica , Salmonella typhimurium/genética , Salmonella typhimurium/patogenicidad , Abastecimiento de Agua , Agricultura , Proteínas Bacterianas/biosíntesis , Bioensayo , ADN Bacteriano/análisis , Proteínas de Unión al ADN/biosíntesis , Frutas , Análisis de Supervivencia , Transactivadores/biosíntesis , Verduras , Virulencia , beta-GalactosidasaRESUMEN
The purpose of this research was to assess growth response of a Salmonella typhimurium poultry marker strain to fresh homogenized vegetables. Salmonella growth rates were significantly higher (p<0.05) in jalapeno extracts than any other produce extract examined. Growth rates on samples of broccoli and lettuce extracts were greater (p<0.05) than the respective growth rates on bell pepper and tomato. Broccoli extracts yielded the highest extent of growth (4 h optical density) followed by jalapeno and bell pepper extracts. From this study, it appears that fresh produce extracts have different abilities to significantly alter growth response in Salmonella. This could potentially be explained by the variations of pH, nutrient availability to the bacteria, or unknown components found within fresh produce.
Asunto(s)
Extractos Vegetales/farmacología , Aves de Corral/microbiología , Salmonella typhimurium/efectos de los fármacos , Salmonella typhimurium/crecimiento & desarrollo , Verduras/química , Animales , Salmonella typhimurium/clasificaciónRESUMEN
Among 43 monozygotic (MZ) and 19 dizygotic (DZ) pairs in which an index case had definite Parkinson's disease (PD), only one MZ pair was definitely concordant for PD. When pairs with questionable clinical features were included, 4 of 48 MZ and 1 of 19 DZ pairs were concordant. The frequency of PD in MZ cotwins of index cases with PD was similar to that expected in an unrelated control group matched for age and sex. Although we were unable to identify a single environmental agent, we conclude that the major factors in the etiology of PD are nongenetic.