Detection of Mex Efflux Pumps in Pseudomonas aeruginosa using a Multiplex Phenotypic and Genotypic Procedure in an Iranian Referral Hospital

Background: The multidrug resistance phenotype of Pseudomonas aeruginosa is largely attributable to expression of Mex efflux pumps. Detection of such pumps expression in different clinical setting would help to select the best antibiotic treatment of choice. Materials and Methods: A multiplex phenotypic and genotypic method was applied for the differential recognition of resistance mediated by the four major transporters, including MexAB-OprM, MexCD-OprJ, MexEF-OprN, andMexXY-OprM. The multiplex approach was performed on 40 selected clinical isolates. Minimum Inhibitory Concentration (MIC) method was respectively used for phenotypic detection using reporter antibiotics Carbenicillin,Erythromycin,Norfloxacin,Imipenem and gentamicin. Genotype was detected using semi-quantitative and quantitative competitive real-time PCR of mex C and mex Eandmex A and mex X, respectively. Both methods were relevant with good levels of overexpression. Results: There were compare and research between phenotypic and genotypic methods in control strains for allmentioned pumps. Among clinical isolates, similarity was observed in 28 out of 40 strains for MexAB-OprM and MexCD-OprJ, and in 32 out of 40 strains for MexXY-OprM and MexEF-OprM. Conclusion: Our results validate the multiplex phenotypic and genotypic as a suitable methodsfor the diagnosis of resistance mediated by four Mex efflux pumps in P. aeruginosa and consequently application of the correct antibiotic.