STUDY THE EXPRESSION OF MEXAB-OPRM PUMP GENES IN CLINICAL ISOLATES OF PSEUDOMONAS AERUGINOSA USING RT-PCR METHOD

Pseudomonas aeruginosa is an opportunistic bacterium that is intrinsically resistant to different antimicrobial substances. One reason for this resistance is the expression of multiple drug efflux pumps, such as MexAB-OprM. Analysis of expression of the MexAB–OprM pump such as mexA with RT-PCR especially with commercial kit can largely aid in selection of suitable antibiotic treatment. Thus, the aim of this investigation was to study the expression of mexA and oprM genes using RT-PCR in clinical isolates. Following the extraction of RNA from 17 clinical isolates and synthesis of cDNA, the relative quantification of mexA and oprM genes were determined by RT- PCR with and without commercial kit, respectively. Over-expression of both mexA and oprM genes were seen in eight clinical isolates. This over-expression corresponded to 2-4 fold increase in MIC for carbenicillin.. The convergence between results obtained from using and not using the kit. Moreover, the convergence between only MIC for carbenicillin among several antibiotics used in phenotypic method and the expression of MexAB-OprM pump was found in all clinical isolates. Therefore, the application of phenotypic method and analysis of gene expression using RT- PCR with commercial kit, due to its ease of working, simultaneously is recommended.