Phenotypic and genotypic detection of metallo-β-lactamases in A. baumanii isolates obtained from clinical samples in Shahrekord, southwest Iran

Abstract

Objective: Acinetobacter baumanii is a pathogenic bacterium that is the cause of many nosocomial infections. This study aimed to determine metallo-β-lactamases (MBL) produced by the A. baumanii isolates obtained from clinical samples in Shahrekord, southwest Iran. Results: A total of 100 A. baumanii were isolated from 250 clinical samples between June 2013 and June 2014. Then, the isolates were identified by biochemical tests, and MBL screening was conducted by the phenotypic tests modified Hodge, EDTA-disk synergy (EDS), combined disk (CD) and AmpC disc after antibiotic sensitivity test. Using PCR technique the bla genes were detected. Eighty-five (85%) isolates were resistant to meropenem and imipenem. Phenotypic tests showed that out of the 100 isolates, 46, 59, 50, 65 and 65 isolates were positive: AmpC disk, CD, EDS, Modified Hodge and E-Test MBL respectively. Gene detection by PCR showed that 23 isolates carried the VIM-1 gene and only three isolates carried the IMP-1 gene. The prevalence of metallo-β-lactamases isolates containing A. baumanii is increasing. Furthermore, the coexistence of various carbapenemases is dominantly act as a major problem. Continuous monitoring of the infections related to these bacteria should be considered to plan an alternative and new therapeutic strategies.