Distribution and Characteristics of Enterotoxigenic and Methicillin-Resistant Staphylococcus aureus in the Nares of Humans and Animals

Abstract

Nasal samples of humans and animals were examined for the presence of Staphylococcus aureus, and subsequently the incidence of enterotoxigenic and methicillin-resistant S. aureus. Additionally, characteristics of the isolates were studied. The carrier rate of S. aureus was 42.7% (38/89) for humans, 86.4% (57/66) for pigs, 19.8% (20/101) for cows, and 9.5%(4/42) for chickens. By using a commercial SET-RPLA kit, 22 isolates from humans produced staphylococcal enterotoxin (SE) A (n=8), SEB (n=9), and SEC (n=5). S. aureus isolates were subjected to genotyping analysis for detection of se genes (sea to see, seg, seh and sei). The se genes were detected in 25 (65.8%) of 38 human, 34 (59.6%) of 57 pig, and 4 (100%) of 4 chicken isolates. Twenty-five human isolates possessed the sea (n=8), seb (n=4), seb-seg-sei (n=5), sec-sei (n=4), sec-seg-sei (n=1) or seg-sei (n=3) genes. Thirty-four isolates from pigs and 4 isolates from chickens possessed seg-sei genes.
MRSA was detected from only 5 food handlers. Phenotypic and genotypic characteristics of 3 MRSA isolates from the 3 food handlers in the same facility were identical except for two phenotypic characteristics. Therefore, the results may suggest that the horizontal transmission of MRSA occurred in the facility.