Involvement of the Multidrug Efflux Pumps in Betalactams Resistant Pseudomonas aerugionsa Clinical Isolates Collected from Burn Patients in Iran.

BACKGROUND: Multi-drug resistant P. aeruginosa has been increasing worldwide. Various mechanisms create this cross resistance in this bacterium including, acquisition beta-lactamases and intrinsic mechanisms, such as the presence of multidrug efflux pumps. Generally, multidrug efflux pumps inhibitor is used as a phenotypic method for the detection of active efflux pump systems.

METHODS: In this study, 100 P. aeruginosa were collected from burn patients. Cefepime and imipenem resistant strains were isolated by disc diffusion agar and MIC. Carbonyl cyanide m-chlorophenyl hydrazone (CCCP), H+ conductor was used to detect activities of multidrug efflux pumps. The multidrug efflux genes of mexA, mexC and mexX were detected by PCR.

RESULTS: 87% and 79% of isolates were cefepime and imipenem resistant respectively. Only 18% of cefepime and imipenem resistant strains were inhibited by CCCP. 98% and 97% of isolates harbored mexA and mexC genes, respectively, while all of them harbored mexX.

CONCLUSION: Thus, cross resistance in P. aeruginosa isolates can be obtained by multidrug efflux pump systems. Therefore, the inhibition of multidrug efflux pumps can be very helpful for the treatment of infections caused by multi drug resistant P. aeruginosa.