Antimicrobial susceptibility and analysis of macrolide resistance genes in Streptococcus pneumoniae isolated in Hamadan

Objective(s): Macrolide resistant Streptococcus pneumoniae pose an emerging problem globally. The aim of this study was to investigate the prevalence of ermB and mefA genes (macrolide resistant genes) by polymerase chain reaction (PCR) method and to detect drug resistance patterns of S. pneumoniae isolated from clinical samples to macrolides and other antibiotic agents by E-test method. Materials and Methods: Fifty five isolates of S. pneumoniae were obtained from clinical samples with microbial tests. The antibiotic susceptibility of isolates for erythromycin, azithromycin, clarithromycin, ceftazidime, ciprofloxacin and vancomycin were determined by E-test method. Genotypic antibiotic resistance pattern was determined by PCR with primer designed for ermB and mefA genes. Results: The number of S. pneumoniae isolates resistance to erythromycin, azithromycin, clarithromycin, ceftazidim, ciprofloxacin were 25.5%, 18.2%, 16.4%, 21.8% and 10.9%, respectively while no resistance to vancomycin was observed. The macrolide resistance genes of ermB and mefA were found in 10.9% and 18.2% of the isolates, respectively. Conclusion: The result of the current study suggests the necessity of evaluation the changes in MIC (minimum inhibitory concentration) values as well as genetic mutations to estimate the prevalence of the resistance antimicrobial agents in S. pneumoniae.