Azam Aghili Amjad - Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran
Mohammad Niakan - Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran
Fatemeh Sameni - Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran
Shahriar Bakhti - Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran
Mansoor Khaledi - Biology Research Center, System Biology and Poisoning Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
Hamed Afkhami - Department of Microbiology, Faculty of Medicine, Shahed University, Tehran, Iran
Reza Mirnejad - Biology Research Center, System Biology and Poisoning Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran

Introduction: Acinetobacter baumannii is one of the most important causes of nosocomial infections. In this bacteria, several mechanisms contribute to resistance against antimicrobial agents. The present study investigated the prevalence of adeS and adeH genes and the role of efflux pumps in imipenem and colistin-resistant A. baumannii clinical isolates. Methods: This study included ۶۰ A. baumannii isolates collected from medical centers affiliated with the Shahid Beheshti University of Medical Science, Tehran, Iran. The antibiotic susceptibility pattern was examined using the broth microdilution MIC method according to Clinical and Laboratory Standards Institute (CLSI) guidelines. Also, the adeS and adeH genes were amplified by PCR. Results: The isolates were ۱۰۰% imipenem-resistant and ۸۶.۷% colistin-resistant. All isolates were positive for the ۵۱-blaOXA gene. The adeH and adeS genes were detected in ۹۵% and ۸۰% of the isolates. Conclusion: The high frequency of adeS and adeH efflux pump genes and the high drug resistance in A. baumannii clinical isolates indicated that adeS and adeH efflux pump genes contribute to antibiotic resistance in this species. Therefore, our results provide essential information about high drug resistance in A. baumannii clinical isolates that can help limit the horizontal and vertical transmission of efflux pump genes in antibiotic-resistant A. baumannii isolates that causes nosocomial infections in susceptible strains.

Acinetobacter baumannii, Efflux pump, adeS gene, adeH gene