Evaluation of MexB and MexY Genes Expression in Carbapenem-Resistant Pseudomonas aeruginosa Strains Isolated from Educational Hospitals of Qazvin and Tehran, Iran

Background: Pseudomonas aeruginosa is one of the most common Gram-negative pathogen causing nosocomial infection worldwide. The emergence of multi-drug resistant strains has become a major clinical concern in recent years. Resistance-nodulation-cell division (RND) family efflux pumps play an important role in the development of multidrug resistance in P. aeruginosa. Objectives: The aims of the present study were to evaluate the antimicrobial susceptibility against carbapenems used and to evaluate the gene expression of two resistance nodulation cell division-type efflux pump systems (MexB and MexY) among carbapenem non-susceptible P. aeruginosa. Methods: Atotal of 256 non-repetitive P. aeruginosa were collected from the different clinical samples of patients admitted in Qazvin and Tehran educational hospitals. Antimicrobial susceptibility testing was performed by standard Kirby-Bauer method. The expression of MexB and MexY genes was assessed by quantitative real-time polymerase chain reaction (qRT-PCR). Results: In total, 107 (41.8%) isolates werenon-susceptible toimipenemand/ormeropenem. Allcarbapenemnon-susceptible isolates were positive for the presence of MexB and MexY genes. The expression of MexB (P value = 0.004) and MexY (P value = 0.001) genes was significantly increased, compared to standard carbapenem sensitive strains. Conclusions: The findings of the present study showed the considerable presence of carbapenem resistance among the clinical isolates of P. aeruginosa. The overexpression of MexB and MexY genes is also established among these resistant isolates collected from studied hospitals in Iran.