title: Evaluation of efflux pumps gene expression in resistantPseudomonas aeruginosaisolates in an Iranian referral hospital.
abstract: OBJECTIVE
  Pseudomonas aeruginosa(PA) is one of the most important causes of nosocomial infections and has an intrinsic resistance to many antibiotics. Among all the resistance-nodulation-division (RND) pumps ofP. aeruginosa,MexAB-OprM is the first efflux pump found to target multiple classes of antibiotics. This study was aimed to evaluate the expression level of genes expressing MexAB-OprM in clinical isolates ofP. aeruginosa.
  
  
  METHODS
  In this study, 45P. aeruginosastrains were isolated from patients admitted to Children's Medical Center Hospital, an Iranian referral hospital. Disk diffusion and Minimum Inhibitory Concentration (MIC) methods were used for determination of the patterns of resistance to antibiotics. Real-time PCR was used to investigate the expression level of genes of MexAB-OprM efflux pump.
  
  
  RESULTS
  Among 45 resistant PA isolates, the frequency of genes overexpression was as follows:MexA(n=25, 55.5%),MexB(n=24, 53.3%) andOprM(n=16, 35.5%). In addition, in 28 strains (62%) overexpression was observed in one of the studied three genes of MexAB-OprM efflux pump.
  
  
  CONCLUSIONS
  In our study 28 isolates (62%) had increased expression level of efflux pumps genes, MexAB-OprM. Although the efflux pumps play important roles in increasing the resistance towards different antibiotics but the role of other agents and mechanisms in evolution of resistance should not be ignored. Since the concomitant overproduction of other Mex efflux systems might have additive effects on antibiotic resistance, the co-expressing of a multicomponent efflux pump is recommended. On the other hand, the concomitant overproduction of two Mex pumps might have additive effects on resistance to antibiotic. Therefore co-expressing of Mex efflux systems is recommended.
authors.affiliation: Pediatrics Infectious Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Babak
authors.initials: B
authors.lastname: Pourakbari
authors.affiliation: Department of Microbiology, Islamic Azad University (Damghan Branch), Damghan, Iran.
authors.forename: Sahar
authors.initials: S
authors.lastname: Yaslianifard
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Alborz University of Medical Sciences, Karaj, Iran.
authors.forename: Somaye
authors.initials: S
authors.lastname: Yaslianifard
authors.affiliation: Pediatrics Infectious Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Shima
authors.initials: S
authors.lastname: Mahmoudi
authors.affiliation: School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Keshavarz-Valian
authors.affiliation: Pediatrics Infectious Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Infectious Diseases, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Setareh
authors.initials: S
authors.lastname: Mamishi
keywords: Efflux pump; Pseudomonas aeruginosa; Real-time PCR