Background: Pseudomonas aeruginosa is one of the most important causes of opportunistic infections.
Carbapenems are administrated for the treatment of resistant infections due to this bacterium. The aim of this
study was to investigate the presence of blaSHV, blaTEM, blaCTX-M and blaOXA-48 beta-lactamase genes in clinical
isolates of P. aeruginosa in Bandar Abbas, Iran.
Methods: In this descriptive study, 96 isolates of P. aeruginosa were obtained from clinical samples in Bandar
Abbas. All isolates were identified by biochemical tests. The antibiotic susceptibility was examined by disk
diffusion method. The presence of blaCTX-M, blaSHV, blaTEM and blaOXA-48 genes was evaluated by polymerase chain
reaction using a specific primer.
Results: In this study, 76 isolates of P. aeruginosa (79.2%) were resistant to at least one carbapenem. The
highest bacterial resistance (100%) was obtained to nalidixic acid (30 µg), followed by tetracycline (30 µg)
and amoxicillin (25 µg). The frequencies of blaCTX-M, blaSHV, blaTEM and blaOXA-48 genes were 23.95% (23 isolates),
23.08% (26 isolates), 57.29% (55 isolates) and 12.5% (12 isolate), respectively. Sixty isolates resistant to
carbapenems (78.9%) carried at least one resistant gene (blaTEM, blaSHV, blaCTX-M and blaOXA-48) and 16 isolates
(21.1%) did not have any of these genes.
Conclusions: This study revealed the prevalence of carbapenem-resistant phenotype of P. aeruginosa clinical
isolates and the frequency of extended-spectrum β-lactamase genes have increased.