Prevalence of Class I and II Integrons of Methicillin-Resistant Staphylococcus aureus Isolates from Hospitals in Hamadan, Iran

In recent years, the role of integrons has been identified in the transfer of antibiotic resistance genes. The aim of this study was to determine the antibiotic resistance pattern and to identify class I and II integrons and associated gene cassettes in clinical isolates of methicillin-resistant Staphylococcus aureus.
In this descriptive cross-sectional study, 100 isolates of S. aureus were isolated from clinical samples in 2015. After cultivation, the isolates were verified by standard biochemical tests. Then, PCR test was used on nuc gene for final confirmation of the isolates and presence of methicillin-resistance gene. Then, methicillin-resistant isolates were tested for susceptibility to 9 antibiotics. Finally, identification of Class I and II integrons genes and associated gene cassettes was performed on mecA gene using PCR method. Data analysis was carried out using Chi square test.
Forty-one out of 100 S. aureus isolates carried mecA gene. The most frequent antibiotic resistance was for cefoxitin and tetracycline (41 and 36 isolates, respectively) and the lowest resistance was reported for vancomycin (0). In this study, The prevalence of 38 isolates (92.68%) and 3 isolates (7.31%) produced class I and II integrons. One type of gene cassette was identified in these isolates, which was related to aadA1 gene cassette.
The results of the current study were indicative of high prevalence of antibiotic resistance and class I integrons in S. aureus isolates carrying mecA gene.