Investigating the Antibiotic Resistance Prevalence and Phenotypic and Genotypic Evaluation of AcrAB-OprM Efflux Pump in Multidrug-resistant in Clinical Isolates of Moraxella catarrhalis in Kazerun City, Iran

Moraxella catarrhalis a gram-negative bacterium, is a significant cause of lower and upper respiratory infections. The RND family efflux pumps lead to multidrug resistance in gram-negative bacteria. One of the well-known pumps in M. catarrhalis is AcrAB-OprM system. This study aimed to investigate the antibiotic resistance in M. catarrhalis and to determine its antibiotic resistance dependence on the efflux pump.

In this study, 137 different clinical samples were collected. M. catarrhalis isolates were confirmed by biochemical assays and PCR. The antibiotic susceptibility pattern was investigated by disc diffusion method according to CLSI. Phenotypic study of the efflux pumps activity was done using cartwheel method. Study of the acra, acrb, and oprm genes were performed by, PCR. In addition, the association of efflux pump with antibiotic resistance was investigated using phenylalanine-arginine β-naphthylamide.

Of 10 isolated M. catarrhalis, 70% (7 isolates) showed multiple antibiotic resistance. The resistance to cefazolin, ceftazidime, tetracycline, chloramphenicol, and ciprofloxacin antibiotics was also dependent on the efflux pump.

The results showed that multiple antibiotic resistance has increased in Moraxella catarrhalis. The 70% presence of acra, acrb, oprm efflux genes of the efflux pumps in this bacterium and antibiotic resistance reduction in the presence of efflux pump inhibitor shows the importance of examining these genes’ presence to suggest a suitable treatment model for the patients infected with M. catarrhalis.