The Evaluation of Efflux Pump Genes norA, norB and norC Related to Fluoroquinolones Resistance in Staphylococcus aureus Strains Isolated from Blood Infection

Abstract

Background & Objective: Recently, ciprofloxacin resistance in Staphylococcus aureus strains, due to efflux pumps, has become a significant challenge. Therefore, this study was performed to evaluate the frequency of norA, norB, and norC efflux pump genes and their roles in resistance to ciprofloxacin in clinical isolates of S. aureus. Materials & Methods: A total of one hundred clinical blood samples were collected from patient in Qom hospitals and S. aureus isolates were identified by standard microbiological tests. Antimicrobial susceptibility patterns were determined by the disk diffusion method using CLSI guidelines. Subsequently, the presence of norA, norB, and norC efflux pump genes in ciprofloxacin isolates was detected using the PCR method. Results: Among one hundred clinical samples, 36 S. aureus isolates were recovered and the results of antibiotic susceptibility tests showed that twenty of them were resistant to ciprofloxacin. 15 isolates were resistant to norfloxacin and one isolate was resistant to ofloxacin. Moreover, the norA, norB, and norC genes were found in 58%, 30%, and 41% of ciprofloxacin-resistant isolates, respectively. Conclusion: Based on the results of this study, norA, norB, and norC efflux pumps may play a significant role in the development of resistance to ciprofloxacin in clinical isolates of S. aureus. Detecting these genes may prove useful in suggesting an effective treatment model for infections caused by S. aureus.

Keywords

• staphylococcus aureus
• blood infection
• bacterial drug-resistance
• efflux pump