OCCURRENCE OF LISTERIA MONOCYTOGENES, STAPHYLOCOCCUS AUREUS AND SALMONELLA SPP IN GREEK WHEY CHEESES IN THE PREFECTURE OF TRIKALA

摘要

Myzithra and Anthotyros are Greek traditional whey cheeses. Considering that fresh whey cheeses have high moisture content, high pH (>6.0) and a low salt content, these dairy products are very susceptible to microbial spoilage and are showing an increased potential for survival/growth of pathogens. Moreover, contamination of these cheeses may further occur during production, storage and in retail shops. The aim of this work was to study the presence of the pathogens Listeria monocytogenes, Staphylococcus aureus and Salmonella spp in samples of Greek whey cheeses Myzithra and Anthotyros from retail shops located in the prefecture of Trikala, Greece. 50 samples of whey cheeses (20 samples of Myzithra and 30 samples of Anthotyros), were collected. The microbiological examination of samples was performed using selective growth media and subsequent confirmation by serological and biochemical methods. The samples with populations of S. aureus higher than 105 cfu/g were furthermore tested for the presence of staphylococcal enterotoxins by using an enzyme-linked immunosorbent test. Microbiological analysis showed that the populations of S. aureus in 6 samples (3 Myzithra and 3 Anthotyros) were higher than 10s cfu/g. These samples were furthermore tested for the presence of staphylococcal enterotoxins and all were found negative. L. monocytogenes was isolated from 2 samples of Myzithra and 4 samples of Anthotyros, whereas the populations of the pathogen were lower than 100 cfu/g in all positive samples. Salmonella spp was not detected in any of the samples.