Comparison of Staphylococcus aureus isolates from food handlers, raw bovine milk and Minas Frescal cheese by antibiogram and pulsed-field gel electrophoresis following SmaI digestion

During a year (from February/2004 to March/2005) 140 samples of food handlers (92), raw milk (24) and Minas Frescal cheese (24) were analyzed for the presence of Staphylococcus aureus in a dairy processing plant of Goiás State, Brazil. Seventy-three S. aureus isolates were obtained and compared by antimicrobial susceptibility and by the DNA macrorestriction patterns obtained from pulsed-field gel electrophoresis following SmaI digestion in order to investigate the possible sources of cheeses contamination. The results showed high diversity among the strains, demonstrating a lack of predominance of an endemic clone in the dairy plant. Based on the results, the raw milk appears to be the most probable source of S. aureus contamination in cheeses.