High prevalence of OXA-type carbapenemases among Acinetobacter baumannii strains in a teaching hospital of Tehran.

Nosocomial infection caused by carbapenem-resistant Acinetobacter baumannii (CRAB) has created a public health concern all around the world. In this study, 100 isolates of CRAB from hospitalized patients during 2015-2016 at Imam Khomeini Hospital were investigated to determine the rates of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains using Kirby-Bauer disk diffusion method. The minimum inhibitory concentrations (MICs) of six antibiotics were determined by broth microdilution method. Multiplex polymerase chain reaction (PCR) was performed to detect bla and bla, bla, and bla that are encoding resistance to carbapenems. All CRAB isolates were MDR and XDR and 2% of them were pandrug-resistant (PDR), whereas colistin, polymyxin B, and tigecycline were the most effective agents. All isolates were positive for bla by PCR. The frequency of bla and bla was 81% and 22%, respectively. Findings of this study showed that very few therapeutic options remained for the treatment of CRAB infections and bla is a dominant resistance gene in CRAB at this hospital.