Occurrence and characterization of enterotoxigenic Staphylococcus aureus isolated from minimally processed vegetables and sprouts in Korea

Staphylococcus aureus has long been recognized as an important pathogen in food-borne disease in the world. Minimally processed vegetables and sprouts are often contaminated with enterotoxigenic strains of this bacterium. This paper reports the results of a 3-year survey (2006-2008) on the occurrence of S. aureus in minimally processed vegetables and sprouts. Of 345 examined samples, 40 samples (11.6%) were contaminated with S. aureus. A total of 25 enterotoxigenic S. aureus strains were biotyped and their resistance to antibiotics was examined. Most isolated strains produced Staphylococcal enterotoxin A (SEA) (n=23) followed by Staphylococcal enterotoxin I (SEI) and Staphylococcal enterotoxin G (SEG) and mainly belonged to the human biotype (88%). At least 96.1% of the analyzed strains showed antibiotic resistance properties, while 56% of the analyzed strains exhibited multiple antibiotic resistance to the antibiotics tested. Two of the analyzed strains were resistant to methicillin. Moreover, a strain which had multi-resistance to 6 antibiotics was found. The results indicate that enterotoxigenic, antibiotic-resistant strains of S. aureus are widely proliferated in minimally processed vegetables and sprouts.