Background and Objective: Efflux pumps are one of the major resistance mechanisms in Pseudomonas aeruginosa that inhibit the accumulation of antibiotics in bacterial cells. The aim of this study was determining the effect of carbonyl cyanide 3-chlorophenyl hydrazone (CCCP) and detecting the overexpression of pump MexCD-oprJ in P. aeruginosa isolated from burn patients in Shahid Motahari hospital during 2014 and 2015.

Materials and Methods: This descriptive study was performed on 100 P. aeruginosa isolates from burn patients in Shahid Motahari hospital. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion and broth microdilution methods according to the CLSI guidelines. The effect of CCCP was determined using the broth microdilution method. The expression levels of MexD-oprJ (an efflux pump) was evaluated by Real-Time PCR and finally detection of nfxB mutations was carried out by PCR and sequencing techniques. 

Results: Antibiogram for 100 P. aeruginosa showed maximum susceptibility and resistance to colistin (100%) and ticarcilin (98%), respectively. The inhibitory effect of CCCP was apparently seen in 16 isolates. Real-time PCR results for these strains showed overexpression in range of 0.26-15.34 (mean: 4/1). The PCR and sequencing techniques showed mutations that converts lucin to prolin in position 14 of the protein sequence.

Conclusion: The increase in expression level of efflux pump MexCD-oprJ shows the prevalence of nfxB mutants in burn wound infections. Therefore, use of carbonyl cyanide 3-chlorophenyl hydrazone (CCCP) can help disrupt the function of efflux pumps and improve the effects of antibiotics.