β-lactamase genes in carbapenem resistance Acinetobacter baumannii isolates from a Turkish university hospital

Introduction: The spread of Acinetobacter baumannii, resistant to most of the available antimicrobial agents, is a serious health problem. The high rate of carbapenem resistance among Acinetobacter baumannii isolates is considered as a threat to public health. In this study, we aimed to determine the antibiotic resistance and related genes in carbapenem-resistant Acinetobacter baumannii isolates. Methodology: Ninety six isolates of A. baumannii were included. Antimicrobial susceptibility was performed by Phoenix Automated System and disk diffusion method. Carbapenem resistane was characterized by scrneeing of resistance genes such as bla(TEM), bla(SHV), bla(CTX-M1-2), bla(PER), bla(VEB), bla(KPC), bla(GES), bla(NDM), bla(VIM), bla(IMP) and bla(OXA23-24-51-58) using multiplex polymerase chain reaction. Results: Resistance for the levofloxacin, gentamicin, amikacin, and tigecycline were determined as 96.9%, 93.7%, 72.9% and 45.8% respectively. Colistin was the only susceptible antibiotic against all clinical isolates. All isolates were defined as multidrug resistance and of these, 31.2% were extensively drug-resistant (sensitive only to colistin). B/aoxA-51 and b/aoxA-23 genes were detected in 100% strains while bla(TEM) was found in only 2% strains. There was no amplification for the bla(SHV), bla(CTX-M1-2), bla(PER), bla(VEB), bla(KPC), bla(GES) bla(NDM), bla(VIM), bla(IMP) and bla(OXA24-58) genes. Conclusions: The high frequency of bla(OXA-23) and low frequency of bla(TEM) gene was observed that indicate prevalence of a variety of A. baumannii strains. The rates of resistance genes vary from region to region. Studies are required for the prevention and control of A. baumannii infection and to formulate the strategies of antibiotic usage.