Ocorrência de Staphylococcus aureus e Escherichia coli O157:H7 em rebanhos leiteiros do Estado de São Paulo / Staphylococcus aureus and Escherichia coli O157: H7 occurrence in dairy herds located in São Paulo State

AUTOR(ES)

Helena Fagundes

DATA DE PUBLICAÇÃO

2007

RESUMO

The aim of this study was to verify the occurrence of S. aureus and E. coli O157: H7 in the milk from dairy cows with subclinical mastitis and in the bulk milk from 42 dairy farms located in two regions of São Paulo State (Region 1: São Carlos, Region 2: Ribeirão Preto). Among the S. aureus strains isolated, the aim was to identify the toxin producers and their epidemiological origin. The isolation of S. aureus was conducted using Baird-Parker agar, and the strains were confirmed by catalase, coagulase, thermonuclease, maltose aerobic fermentation and acetoin production. The isolation of E. coli O157: H7 was conducted using Sorbitol MacConkey MUG agar. The strains were confirmed by IMVC and serology using anti E. coli O157 sera. Rapid passive latex agglutination was used for detection of TSST-1 and enterotoxigenic strains of S. aureus. The epidemiological identification was performed using pulsed field gel electrophoresis (PFGE). S. aureus was isolated from 3.9% and 6.7% of the individual milk samples from regions 1 and 2, respectively. Dairy cows belonging to farms with milk production ranging from 400 to 1.000 L/day showed higher risk of S. aureus carrying-over, when compared with dairy farms with milk production <400 L/day and >1.000 L/day. In bulk milk samples, the occurrence of S. aureus was the same in both regions evaluated (19%). The simultaneous production of enterotoxin B and C was observed in 4.7% of strains isolated from individual milk samples, while 4.7% produced both enterotoxin A and TSST-1. TSST-1 production alone was observed in 14.3% of S. aureus strains isolated from individual milk and 25% of bulk milk samples. S. aureus strains tested by PFGE demonstrated genetic similarity, showing the dispersion patterns of this microorganism among dairy farms. E. coli O157: H7 was isolated from 1% and 1.6% of individual milk samples from regions 1 and 2, respectively, although it was not detected in bulk milk samples. The importance of preventive measures to ensure milk quality during milking extraction is stressed, aiming to avoid pathogenic agents, mainly S. aureus, and therefore, to prevent the carry-over of food borne diseases to humans through milk.

ASSUNTO(S)

dairy cows staphylococcus aureus mastite milk quality qualidade do leite escherichia coli o157: h7 public health saúde pública e. coli o157: h7 vacas leiteiras s. aureus mastitis

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