Comparação entre o sistema Petrifilm RSA® e a metodologia convencional para a enumeração de estafilococos coagulase positiva em alimentos
Foods are examined for the presence of coagulase-positive staphylococci using selective and differential media followed by characterization for coagulase, thermoestable nuclease, Gram and catalase tests. These tests may require up to four days to obtain the results, besides time and material used. The Petrifilm® rapid S.aureus count plate is a alternative to traditional methodology. In this study, 62 samples of several foods were analysed comparing the BPA method followed by coagulase or latex agglutination tests and Petrifilm® RSA method. The Petrifilm RSA method was significantly different to BPA method, with higher mean log counts. The BPA method followed by latex agglutination test for typical and atypical colonies were significantly different from the other methods used. The Petrifilm® RSA method is an alternative on enumeration of coagulase-positive staphylococci in foods, because true quantitave results were obtained in approximately 31 hours. Typical and atypical colonies on BPA should be tested to obtain accurate results. This count is more significative when latex agglutination test is used. Food analyses for staphylococci showed several limitations.