Mohammad Hossein Maleki - Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
Zamberi Sekawi - Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, University of Putra, Malaysia
Setareh Soroush - Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran.Department of Microbiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran
Farid Azizi-Jalilian - Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran ۲ Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, University of Putra, Malaysia
Khairollah Asadollahi - Psychosocial Injuries Research Center, Ilam University of Medical Sciences, Ilam, Ira
Sattar Mohammadi - Department of Microbiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran
Mohammad Emaneini - Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Morovat Taherikalani - Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran ۲ Department of Medical Microbiology and Parasitology, Faculty of Medicine and Health Sciences, University of Putra, Malaysia

Objective(s):To date, the most important genes responsible for tetracycline resistance among Acinetobacter baumannii isolates have been identified as tet A and tet B. This study was carried out to determine the rate of resistance to tetracycline and related antibiotics, and mechanisms of resistance.  Materials and Methods: During the years ۲۰۱۰ and ۲۰۱۱, a total of ۱۰۰ A. baumannii isolates were recovered from patients in different hospitals of Tehran, Iran. Antimicrobial susceptibility to tetracycline, minocycline, doxicycline and tigecycline was evaluated by E-test. Polymerase chain reaction (PCR) of the tet A and tet B genes was performed using specific primers, after which the isolates were subjected to Repetitive Extragenic Palindromic-PCR (PCR) to identify the major genotypes. Results: Of all isolates, ۸۹% were resistant to tetracycline (MIC۵۰ = ۳۲ μg/ml, MIC۹۰ = ۵۱۲ μg/ml). Minocycline with the resistant rate of ۳۵% (MIC۵۰ = ۱۶ μg/ml, MIC۹۰ =۳۲ μg/ml) and doxicycline with the resistant rate of ۲۵% (MIC۵۰ = ۱۶ μg/ml, MIC۹۰= ۳۲ μg/ml) have a good activity against A. baumannii isolates. All isolates were sensitive to tigecycline. Frequencies of tet B and tet A genes and coexistence of tet A and tet B among the isolates resistant to tetracycline, were ۸۷.۶%, ۲.۲% and ۱.۱%, respectively. Distribution of REP-types among A. baumannii isolates was types A (۴۰%), B (۳۰%), C (۱۰%), D (۵%) and E (۵%). Conclusion: It seems that tet A and tet B genes play an important role in the induction of resistance towards tetracyclines used in this study. It is suggested that further studies focus on other antimicrobial drugs and combinations in order to achieve a successful therapy against multi drug resistance (MDR) A. baumannii strains in Iran.  

Acinetobacter baumannii, REP-PCR, Tet A, Tet B, Tetracycline resistance