Susceptibility Pattern and Distribution of Oxacillinases andblaPER-1Genes among Multidrug ResistantAcinetobacter baumanniiin a Teaching Hospital in Iran

Abstract

Acinetobacter baumannii (A. baumannii)is an important nosocomial pathogen in healthcare institutions.β-Lactamase-mediated resistance is the most common mechanism for carbapenem resistance inA. baumannii. The aim of this study was to determine the antibiotic resistance pattern, to detectOXAencoding genes, class A,blaPER-1, and to detect the presence of ISAba1. A total of 124A. baumanniiisolates were collected from hospitalized patients in a teaching hospital in Kashan, Iran. The susceptibility of isolates to different antibiotics was determined by disk-diffusion method. PCR was used to detectblaPER-1,blaOXA-23,blaOXA-24,blaOXA-51,blaOXA-58, and ISAba1 genes. All isolates were resistant to ceftazidime, ceftriaxone, and cefotaxime. All of the isolates revealed susceptibility to polymyxin B and colistin. Ninety-six percent of the isolates were extensive drug resistance (XDR), 5.6% extended spectrum beta-lactamase (ESBL), and 54.8% metallo-beta-lactamase (MBL). All isolates were positive forblaOXA-51and ISAba1.blaOXA-23,  blaOXA-24, andblaOXA-58were found in 79.8%, 25%, and 3.2%, respectively. The frequency rate ofblaPER-1gene was 52.4%. Multidrug resistantA. baumanniiisolates are increasing in our setting and extensively limit therapeutic options. The high rate presence of class D carbapenemase-encoding genes, mainlyblaOXA-23carbapenemases, is worrying and alarming as an emerging threat in our hospital.