Toxigenicity and genetic diversity of Staphylococcus aureus isolated from Vietnamese ready-to-eat foods

The aim of this study was to investigate the prevalence and genetic diversity of Staphylococcus aureus and staphylococcal enterotoxins (SEs) in ready-to-eat foods marketed in Hanoi, Vietnam. Out of 212 samples tested, 45 were contaminated with this bacterium and 18 contained strains having classical SEs. Among different food products, the bacterial occurrence ranged between 12.5% and 35.4% and milk samples had the highest prevalence. The production of SEs varied according to the food types and 26 different ribotype patterns were observed among the 45 strains. Our dendogram analysis showed the existence of many clones without clear-cut affiliation to any particular food type indicating both diverse primary and secondary contamination sources. The SEs also occurred in a wide variety of genetically different S. aureus strains which might facilitate the bacterium with better ecological fitness to cause epidemics. It can be concluded that Vietnamese ready-to-eat foods pose a high risk of contamination by toxigenic S. aureus population urging the need of implementing proper hygienic practices.