Antimicrobial resistance patterns and their encoding genes among Acinetobacter baumannii strains isolated from burned patients.

The purpose of this study was to determine the mechanisms and patterns of antimicrobial resistance among the isolates obtained from burned patients with wound infections at a teaching hospital in Tehran, Iran. A total of 23 Acinetobacter baumannii isolates were collected from patients with burn wound infections between August 2009 and July 2010 from a hospital in Tehran. The susceptibility of these strains against 11 antimicrobial agents was determined by E-test according to the CLSI guidelines. All the resistant strains were then subjected to PCR assay for 28 distinct resistance genes. The most active antimicrobial agent was colistin with 100% sensitivity followed by gentamicin, amikacin and imipenem with 69.5%, 52.1% and 51.1% sensitivity, respectively. The most frequent resistance genes detected were bla(OXA-51-like) genes (n=23; 100%) that was intrinsic to A. baumannii isolates, gyrA (n=23; 100%), carO (n=23; 100%), tetA (n=22; 95.5%), tetB (n=15; 65.2%), intI (n=13; 56.5%) and PER (n=12; 52.1%), respectively. In order to make a proper choice of antibiotic for burn patients, it would be beneficial to physicians to identify drug resistance patterns in A. baumannii isolates.