Determination of extended spectrum beta-lactamases, metallo-beta-lactamases and AmpC-beta-lactamases among carbapenem resistant Pseudomonas aeruginosa isolated from burn patients

Background: Pseudomonas aeruginosa is an important cause of morbidity and mortality in patients with burns. Method: A total of 214 nonduplicated burn wound isolates of P. aeruginosa were recovered from burn patients. Identification of carbapenem resistant isolates and their antimicrobial susceptibility pattern was carried out using the phenotypic methods. The presence of genes encoding extended spectrum beta-lactamases (ESBLs) and metallo-beta-lactamases (MBLs) enzymes were determined by PCR. The genetic relationships between carbapenem resistant isolates were determined by Random Amplified Polymorphic DNA (RAPD)-PCR. Results: Of 214 investigated P. aeruginosa isolates, 100 (46.7%) were carbapenem resistant. All carbapenem resistant P. aeruginosa were resistant to imipenem, meropenem, ertapenem, carbenicillin, aztreonam, gentamicin and ciprofloxacin but susceptible to polymyxin B. Among 100 carbapenem resistant P. aeruginosa isolates, 3%, 65% and 52% were identified as ESBLs, carbapenemase and AmpC overproduction positive isolates respectively. The most prevalent ESBLs and MBLs genes included bla(OXA-10) (97%), bla(TEM) (61%), bla(VIM) (55%), bla(PER) (13%), bla(IMP) (3%) and bla(AIM) (1%). RAPD analysis yielded 13 distinct profiles among 92 isolates. A dominant RAPD type was designated as A that consisting of 80 isolates. Conclusion: This is the first report of Adelaide IMipenmase (AIM) MBLs producing P. aeruginosa from Iran and also of the high prevalence of AmpC overproduction isolates. According to the results of current study, P. aeruginosa isolates producing OXA-10, TEM, VIM, PER and IMP beta-lactamases are frequent and the population structures of these isolates are highly similar. (C) 2014 Elsevier Ltd and ISBI. All rights reserved.