engleski

Occurrence, enterotoxin production and antimicrobic susceptibility of Staphylococcus aureus isolates from domestic cheeses in the Dubrovnik area

Staphylococcus aureus is a well-known opportunistic pathogen that causes a wide range of acute and chronic diseases in both humans and animals. Staphylococcal food poisoning is just one of many diseases caused by this bacterium. The causative agents are enterotoxins produced by enterotoxigenic strains of S. aureus during its growth in favourable conditions in food. Epidemiological data show that S. aureus is often found in raw milk cheeses and accordingly, cheeses are often implicated in food poisoning outbreaks. Since there are no data on the nature of S. aureus isolated from cheese produced in Croatia, the aim of this study was to determine the occurrence, enterotoxin production capability and antimicrobic susceptibility of S. aureus isolates from domestic cheeses produced in the Dubrovnik area. A total of 30 cheese samples were analysed, and 18 samples (60%) were highly contaminated with S. aureus strains. The contamination level ranged from 3.94 to 6.26 log10 cfu/g. Such a high level of contamination was supported by an inappropriate temperature regime above 8°C during market sale. Although highly contaminated, staphylococcal enterotoxins were not detected in any of the cheese samples. A total of 180 coagulase- positive isolates were collected from 18 cheese samples, 175 of which were confirmed as S. aureus by the latex agglutination test. Enterotoxin production was detected in 35 iso- lates (20%), and of these 32 isolates produced staphylococcal enterotoxin C. The other three isolates presumably produced enterotoxin E. Antibiotic resistance was detected in 1.1% of isolates and only to mupirocin. However, a full comprehensive conclusion on the nature of S. aureus isolates cannot be achieved without determining its genotype characteristics for the presence of staphylococcal enterotoxin genes and molecular typing, to determine the origin of the isolates.

Staphylococcus aureus ; cheese ; staphylococcal enterotoxins ; antimicrobial susceptibility

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