Investigation of efflux pump -activated fluoroquinolone resistance in Pseudomonas aeruginosa multiple drug resistant isolates by carbonyl cyanide-m-chlorophenyl hydrazone inhibitor (CCCP)

One of the problems with Pseudomonas aeruginosa-related infections is prevalence of Multiple-Drug Resistant isolates. Bacterial efflux pumps are capable of a wide range of antibiotics and detergents to efflux out of the cell. The aim of study was determining efflux pumps activity in fluoroquinolones resistant MDR strains of Pseudomonas aeruginosa. 50 strains ofPseudomonas aeruginosa were isolated from clinical specimens of patients were admitted to Milad hospital and diagnosed by biochemical tests. Antibiotic susceptibility was determined by disc diffusion method according to CLSI. After determining the MDR isolates, for evaluation of efflux pump activity the MIC of ciprofloxacin, levofloxacin was determined before and after treatment by CCCP inhibitor. 17(34%) MDR strains of Pseudomonas aeruginosa that were resistant to more than two classes of antibiotics were detected. Among flouroqinolon MDR strains of Pseudomonas aeruginosa 2 (11.8%) and 3(17.64%) had MIC reduction of at least 4 times and more for ciprofloxacin and lovofloxacin after carbonyl cyanide-m-chlorophenyl hydrazone (CCCP) effect, respectively. The frequency of MDRPseudomonas aeruginosa are low. Only 4 isolates among MDR bacteria had efflux pump activity. So the efflux pump is not major mechanism for resistance to ciprofloxacin and lovofloxacin among these isolates and further studies about other resistance mechanism is recommended.