Prevalence of Extended-Spectrum beta-Lactamase Genes and Antibiotic Resistance Pattern in Clinical Isolates of Acinetobacter baumannii from Patients Hospitalized in Mashhad, Iran

Background: Carbapenem-resistant Acinetobacter baumannii strains are one of the most severe factors in hospital infection world-wide, in which the beta-lactamase enzyme is one of the main resistance mechanisms. Objectives: This study aimed to evaluate the presence of carbapenem-resistant beta-lactamase genes and determine antibiotic resistance patterns in the clinical isolates of A. baumannii from patients hospitalized in the Shahid Kamyab Hospital, Mashhad, Iran. Methods: Out of 286 collected isolates from patients hospitalized in Shahid Kamyab Hospital (from March 2017 to June 2017), 31 isolates were confirmed to be A. baumannii using biochemical tests. Antibiotic susceptibility testing was conducted using the disc diffusion method according to the CLSI standard protocols. The presence of beta-lactamase genes, namely bla(V)(EB), bla(P)(ER), bla(AmpC), bla(VIM), bla(I)(MP), bla(SHV), and bla(TEM), was detected using polymerase chain reaction. Results: In this study, 31 isolates were identified as A. baumannii, all of which revealed high resistance to ceftazidime, cefixime, ceftriaxone, meropenem, imipenem, cefotaxime and cephalexin. In this case, the lowest resistance (19.35%) was observed against polymixin B. Moreover, bla(AmpC), bla(TEM), bla(SHV), bla(P)(ER), and bla(VIM) were observed in 93.54% (29), 51.61% (16), 48.38% (15), 41.93% (13), and 77% (24) of the isolates, respectively. However, bla(V)(EB) and bla(IMP) were observed in none of the isolates. Conclusions: The results showed high carbapenem resistance and high frequency of beta-lactamase resistance genes among the clinical isolates of A. baumannii.