STUDY THE EXPRESSION OF MEXAB-OPRM PUMP GENES IN LINICAL 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.
Materials & Methods: 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.
Results: Over-expression of both mexA and oprM genes were seen in eight clinical isolates. This overexpression corresponded to 2-4 fold increase in MIC for carbenicillin..
Conclusion: 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