Molecular Epidemiology of Enterotoxins of Staphylococcus aureus from Pets and Their Owners in Northern Taiwan

In order to investigate the Staphylococcus aureus enterotoxin genotypes and phylogenetic relatedness, samples were collected with nasal swab from pet and their owners and using Pulse-field gel electrophoresis (PFGE) patterns of these isolates to analyze their phylogenetic relatedness with enterotoxin genotypes and antimicrobial susceptibility. The commercial RPLA test kit SET-RPLA detecting enterotoxins A, B, C, D, and E was available for this study to compare with the strain genotypes. The results of our previous sampling show that the strains of methicillin-resistant Staphylococcus aureus (MRSA) have a higher percentage (91.3%) of harboring enterotoxin genes than the methicillin-sensitive S. aureus (MSSA) do (57%) (P < 0.01), and the most frequent enterotoxin genotypes detected from free clinical complains pets and humans are sea, seb, sek, sep, seq and egc. To compare the se gene prevalence of isolates from human and pet, the human origins (66/95, 69.5%) were higher than the pet origins (8/21, 38.1%) (P < 0.05). Certain degree of relatedness between enterotoxin genotypes and PFGE phylogenetic dendrogram has been observed, and several enterotoxin genotypes, such as seb, sed, sek, sep, seq and egc have a trend to clump themselves into 60 - 100% cluster similarity. Perhaps that can explain why the distributions of se genes are variable with different origins and areas. Antimicrobial susceptivity test show that MRSAs had a higher resistance to the antibiotics than the MSSAs, and some resistance strains have high phylogenetic relatedness. As these results, S. aureus enterotoxin genes and antimicrobial resistance presents clustered appearance, for the reason that the pathogenic strains should also have their regional and clonal distribution and that would be helpful for tracing the source of pathogenic strain.