Prevalence and distribution of resistance and enterotoxins/enterotoxin-like genes in different clinical isolates of coagulase-negative Staphylococcus.

BACKGROUND Coagulase-negative staphylococcus (CoNS) is considered to be the major reservoirs for genes facilitating the evolution of S. aureus as a successful pathogen. The present study aimed to determine the occurrence of genes conferring resistance to fluoroquinolone, determining of the prevalence of insertion sequence elements IS256, IS257 and different superantigens (SAgs) among CoNS isolates obtained from various clinical sources. MATERIALS AND METHODS The current study conducted on a total of the 91 CoNS species recovered from clinical specimens in Hamadan hospitals in western Iran in 2017-2019. The antimicrobial susceptibility testing was performed using disk diffusion method and the presence of the IS256 and IS257, genes conferring resistance to fluoroquinolone and enterotoxins/enterotoxin-like encoding genes were investigated by polymerase chain reaction (PCR) method. RESULTS Among genes encoding classic enterotoxins, sec was the most frequent which was carried by 48.4% of the 91 isolates, followed by seb in 27.5% of the isolates. None of the CoNS isolates was found to be positive to enterotoxin-like encoding genes. In 11(12%) of all isolates that were phenotypically resistant to levofloxacin, 9 isolates (81.8%) were positive for gyrB, 8 isolates (72.7%) were positive for gyrA, 8 isolates (72.7%) harbored grlB and 7 isolates (63.6%) were found to carry grlA. The IS256 and IS257 were identified in 31.8% and 74.7% of the isolates, respectively. The results of statistical analysis showed a significant association between the occurrence of staphylococcal enterotoxins (SEs) encoding genes and antimicrobial resistance. CONCLUSION Antimicrobial resistant determinants and SEs are co-present in clinical CoNS isolates that confer selective advantage for colonization and survival in hospital settings. The coexistence of insertion elements and antibiotic resistance indicate their role in pathogenesis and infectious diseases.