Susceptibility Pattern and Distribution of Oxacillinases and bla PER-1 Genes among Multidrug Resistant Acinetobacter baumannii in 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 in A. baumannii . The aim of this study was to determine the antibiotic resistance pattern, to detect OXA encoding genes, class A, b l a P E R - 1 , and to detect the presence of ISA ba 1. A total of 124 A. baumannii isolates 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 detect b l a P E R - 1 , b l a O X A - 23 , b l a O X A - 24 , b l a O X A - 51 , b l a O X A - 58 , and ISA ba 1 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 for b l a O X A - 51 and ISA ba 1. b l a O X A - 23 , b l a O X A - 24 , and b l a O X A - 58 were found in 79.8%, 25%, and 3.2%, respectively. The frequency rate of b l a P E R - 1 gene was 52.4%. Multidrug resistant A. baumannii isolates are increasing in our setting and extensively limit therapeutic options. The high rate presence of class D carbapenemase-encoding genes, mainly b l a O X A - 23 carbapenemases, is worrying and alarming as an emerging threat in our hospital.