Detection of some phenotypic and genotypic characteristics of Staphylococcus aureus isolated from food items in the Czech Republic

Abstract

Staphylococcus aureus is an important foodborne pathogen and can produce a wide range enterotoxins, which contribute to food poisoning. The aim of this study was to interrogate foodborne strains of S. aureus for phenotypic and genotypic characteristics. Strains were screened for enterotoxins, hemolysins and antimicrobial resistance, and the genetic relationship between strains was described after pulsed-field gel electrophoresis (PFGE) analysis. Of the S. aureus strains, 82.8 % (n = 93) harboured one or more of the following enterotoxin genes (sea, seb, sec, sed, see, seg, seh, sei, sej); 39.8 % of strains demonstrated se genes and 43 % carried from two to five se genes, while 17.2 % of the strains possessed none of the genes examined. The most commonly detected toxin genes were sea, seb, sec and seg. The presence of genes coding for antibiotic resistance such as blaZ, vanA, vanB and mecA was investigated by polymerase chain reaction (PCR). Seventy-two strains carrying the blaZ gene exhibited phenotypic resistance to ampicillin and penicillin. Ten strains (10.75 %) carried the mecA gene and correspondingly demonstrated resistance to oxacillin. The presence of vancomycin resistance genes, vanA and vanB, was not detected. Genotypic subtyping was performed using PFGE with SmaI restriction enzyme. The genetic relationships between enterotoxin harboring strains and non-enterotoxigenic strains were explored. Twenty-four different pulsotypes were generated from 93 food isolates with a similarity level of 88 %.