Detection of enterotoxigenic and antimicrobial resistant S. aureus in Turkish cheeses

Staphylococcus aureus is a very common microorganism present on the skin and mucosae of humans and animals, and in the environment. Contamination of milk and dairy products may occur directly from infected food producing animals or may result from poor hygiene during production processes or at the retail and storage stage. This study reports the results of an investigation on the presence of enterotoxigenic and antimicrobial resistant S. aureus in Turkish cheeses. A total of 200 unpackaged cheese samples were examined and 19 of them (9.5%) were found to contain coagulase positive Staphylococci (CPS). In 12 samples (6%) S. aureus the mean was 4.31 log cfu/g. Three out of 12 S. aureus strains were found to be enterotoxigenic and two of the three produced only SEC type, one of them produced SEC and SED together. Two of the 12 S. aureus strains were mecA positive. Methicillin-resistant Staphylococcus aureus (MRSA) strains were found to be enterotoxigenic; one strain synthesisedsynthesised SEC and one SEC + SED. In this study, 10 out of 12 strains were found to be resistant to one or more antibiotics tested by the disk diffusion method. All strains were susceptible to vancomycin, gentamicin and imipenem. The results indicate that the presence of enterotoxigenic and antimicrobial resistant strains of S. aureus in cheese constitute a potential risk for public health. This calls for better control of cheese contamination sources and taking hygienic measures is necessary for food safety. (C) 2011 Elsevier Ltd. All rights reserved.