Efflux MexAB-Mediated Resistance in P. aeruginosa Isolated from Patients with Healthcare Associated Infections

Today, one of the most important challenges for physicians is the adequate treatment of infections due to multidrug resistant organism (MDR).Pseudomonas aeruginosais considered an opportunistic organism causing different types of healthcare associated infections (HAIs). We aimed to investigate the MDR and pandrug resistance (PDR) rate inP. aeruginosain our region and detect efflux-pumpmexABgenes and the proposed binding interactions of five different categories of antimicrobial agents with themexBpump. A total of 180 non-duplicatedP. aeruginosa strainswere isolated from patients with HAIs in the Suez Canal University Hospital. Phenotypically, minimum inhibitory concentration (MIC) was done for all MDR and PDR strains before and after addition of efflux pump inhibitor carbonyl cyanide m-chlorophenyl hydrazone (CCCP). Molecular detection ofmexAandmexBgenes was done by using polymerase chain reaction (PCR). Most of the isolated strains (126 strains) were MDR (70%); only 10 samples (5.5%) were PDR.MexAandmexBgenes were detected in 88.2% (120 strains) and 70.5% (96 strains) of stains, respectively. All PDR strains (10 stains) carried bothmexAandmexBgenes. EffluxmexABgenes were detected in all MDR and PDR strains (136 strains). Molecular modeling studies were performed to investigate the modes of intermolecular binding interactions between the antimicrobial agents andmexBkey amino acids that resulted in MDR and PDR. The current study reported high prevalence of MDR and PDRP. aeruginosain patients with HAIs in the Suez Canal University Hospitals.