Disrtibution of blaTEM, blaSHV and blaCTX-M genes among ESBL-producing P. aeruginosa isolated from Qazvin and Tehran hospitals, Iran

Background. Pseudomonas aeruginosa is as an important opportunistic human pathogen, which is associated with several clinical infections that are usually difficult to treat because of resistance to multiple antimicrobials. The production of extended-spectrum Ã-lactamases (ESBLs) is an important mechanism of Ã-lactam resistance. The aims of this study were to determine the prevalence of ESBLs, antimicroboial susceptibility, and to detect the blaTEM, blaSHV, and blaCTX-M genes.Methods. In this study, during March 2013 to December 2014, 266 P. aeruginosa isolates were collected from patients admitted to educational hospitals of Qazvin and Tehran, Iran. All isolates were initially screened for ESBL production by disk diffusion method and were further confirmed using a combined disk method. Antimicrobial susceptibility of ESBL-producing isolates was determined by standard disk diffusion method. PCR and sequencing techniques were employed for detection of blaTEM, blaSHV, and blaCTX-M genes. Results.  In total, 262 (98.5%) P. aeruginosa isolates were non-susceptible to the used extended spectrum cephalosporins, among those 75(28.6%) isolates were ESBL producers. Fifty nine (78.7%) of ESBL-producing isolates showed multidrug resistance pattern. Of 75 ESBL-positive isolates, the blaTEM-1 (26.7%) was the most common gene, followed by blaCTX-M-15 (17.3%), blaSHV-1 (6.7%), and blaSHV-12 (4%) either alone or in combination.Conclusions. The results of this study showed the notable prevalence of ESBLs among the clinical isolates of P. aeruginosa in Iran, indicating the urgency for implementation of appropriate follow-up measures for infection control and proper administration of antimicrobial agents in our medical settings