Fontes de contaminação de Yersinia enterocolitica durante a produção de leite

Abstract

This work was performed in order to determine the possible Yersinia enterocolitica contamination sources at different points of the dairy cows milking process in eight properties of Pelotas, RS, over four different periods distributed in a year. Y. enterocolitica is a psychrotrophic bacterium responsible for causing gastroenteritis in humans, especially in infants and children, from the consumption of contaminated water or food, and raw milk. Raw milk samples were analyzed immediately after milking, water of milking parlor, milker’s hands, milk collection bucket and inflator liners. The samples of raw milk and water were collected in sterile bottles and milker hand samples, bucket and liners were collected with sterile swabs. The raw milk samples were subjected to a pre-enrichment peptone water buffered at 4°C for 30 days and subsequently incubated in PSTA broth ampicillin added at 28°C for 48h. Water samples were filtered through cellulose ester membrane and incubated in TSB medium at 30°C for 24h. The milk samples after incubation in PSTA, the TSB where the membranes used in water filtration were incubated and the material of the hands material, bucket and liners collected in the swabs were plated on MacConkey agar and incubated at 30°C for 24h, to obtain colonies. Characteristics colonies were analyzed by duplex PCR to confirm the species. The molecular profiles of Y. enterocolitica isolates were compared using rep-PCR. Y. enterocolitica was isolated from 9,37% (3/32) of milk samples, 6,25% (2/32) of water samples and 12,5% (4/32) of hand samples. There weren’t similarities in the band profile of the isolates found, however showed the presence of different strains of the same sample, demonstrating a variety of strains distributed in the environment. The presence of Y. enterocolitica in raw milk in Brazil is dangerous, considering that the product is sold clandestinely, exposing consumers to the risk of infection by the bacterium, to consume it without proper heat treatment.