Investigating the Presence of Efflux Pump Genes adeI and adeJ in Clinical Antibiotic-Resistant Isolates of Acinetobacter baumannii

Abstract

Background: Acinetobacter baumannii is one of the most important known causes of hospital infections worldwide that is resistant to many common antibiotics. Efflux pumps are among the main reasons behind resistance in this bacterium. Objectives: This study was conducted to investigate the presence of efflux pump genes (adeI, adeJ) in clinical antibiotic-resistant isolates of A. baumannii in Tehran hospitals. Methods: One hundred fifty clinical samples of wounds, urine, sputum, and blood were collected periodically (6 months) from Tehran hospitals. Acinetobacter baumannii was identified using common biochemical methods. After conducting biochemical tests, the final confirmation of the samples was performed by examining the blaOXA-51-like gene by molecular polymerase chain reaction (PCR) method. The disk diffusion antimicrobial susceptibility testing was performed using Mueller Hinton agar growth medium according to Clinical and Laboratory Standards Institute (CLSI) guidelines on nine antibiotics. Then the samples were investigated for the presence of adeI and adeJ genes. Results: Examining the antibiotic resistance of the isolates showed that the resistance level varied from 48.1% to 98.2%, depending on the antibiotic type. In this study, isolates showed the highest and lowest resistance to tetracycline and gentamicin, respectively. Also, positive isolates for the presence of adeI and adeJ genes showed the highest resistance to tetracycline, amikamycin, ceftazidime, and ceftriaxone. Isolates that were negative for the presence of these two genes showed the highest sensitivity to imipenem, gentamicin, and ciprofloxacin. Conclusions: In this study, the correlation of antibiotic resistance test and PCR results showed that the presence of adeI and adeJ genes in the samples significantly increased the resistance to all investigated antibiotics. Therefore, evaluating efflux pumps proves to be useful in identifying antibiotic-resistant strains and appropriate drug treatment. Of course, the role of other factors in creating resistance should not be neglected.