The Role of MexCD-OprJ and MexEF-OprN Efflux Systems in the Multiple Antibiotic Resistance of Pseudomonas aeruginosa Isolated from Clinical Samples

Increasing antimicrobial resistance and the development of multi-drug resistant (MDR) Pseudomonas aeruginosa is dependent on the expression of efflux pumps. This study aimed to investigate the role of overexpression of MexCD-OprJ and MexEF-OprN efflux pumps in reduced susceptibility to antimicrobial agents among P. aeruginosa strains. Totally, 100 clinical isolates of P. aeruginosa were collected from patients and the strains were identified by standard diagnostic tests. The MDR isolates were detected using the disk agar diffusion method. The expression levels of MexCD-OprJ and MexEF-OprN efflux pumps were evaluated by the real-time PCR. Forty-one isolates showed MDR phenotype, while piperacillin-tazobactam and levofloxacin were the most- and least-effective antibiotics, respectively. Also, all 41 MDR isolates showed a more than tenfold increase in the expression of mexD and mexF genes. In this study, a significant relationship was observed between the rate of antibiotic resistance, the emergence of MDR strains, and increasing the expression levels of MexEF-OprN and MexCD-OprJ efflux pumps (P < 0.05). Efflux systems mediated resistance was a noteworthy mechanism causative to multidrug resistance in P. aeruginosa clinical isolates. The study results demonstrated mexE and mexF overexpression as the primary mechanism conferring in the emergence of MDR phenotypes among P. aeruginosa strains. In addition, we also show that piperacillin/tazobactam exhibited a stronger ability in the management of infections caused by MDR P. aeruginosa in this area.