Prevalence of Oxacillinase Groups I, II and III in Pseudomonas aeruginosa Isolates by Polymerase Chain Reaction and Genotyping by ERIC-PCR Methods

Pseudomonas aeruginosa is main bacterial pathogen accountable for nosocomial infections. Furthermore, it could potentially become resistant to β-lactams, aminoglycosides and fluoroquinolones antibiotics..
The purpose of this study was to determine the antibiotic susceptibility pattern and genotyping of P. aeruginosa in hospitals of Tabriz (Iran) and investigate the prevalence of OXA producer isolates..
Overall, 151 non-replicated isolates of P. aeruginosa were collected from October 2013 until September 2014. Antibiotic susceptibility pattern was determined by disk diffusion (Kirby Bauer) method, according to the clinical laboratory standards institute (CLSI) guideline. Genes encoding OXA (Ambler class D) β-lactamase were detected by PCR for all isolates. Polymerase chain reaction with Enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) primers was used to establish the clonal relationship between the different isolates..
The frequencies of resistance to antibiotics were as follows: gentamicin: 68%, ceftazidime: 67%, piperacillin: 66%, cefepime: 64%, ciprofloxacin: 62%, tobramycin: 61%, amikacin: 60%, imipenem: 52%, gatifloxacin: 28%, polymyxin B: 2 % and colistin: 2%. The OXA group I genes was identified in 82 (56%), the OXA group II gene in 26 (18%), OXA group III in 14 (9%), OXA-1 in 22 (15%) and OXA-4 in 3 (2%) isolates. The ERIC-PCR indicated high genetic diversity among P. aeruginosa isolates..
The high prevalence of OXA β-lactamase and high genetic diversity of P. aeruginosa indicated that the resistance of P. aeruginosa might be expanding in our studied hospitals..