Molecular Detection of Carbapenemases and Extended-Spectrum β-Lactamases-Encoding Genes in Clinical Isolates of Pseudomonas aeruginosa in Iran

Pseudomonas aeruginosa is a unique Gram-negative opportunistic pathogen that is the leading cause of nosocomial infections. This study aimed to investigate the prevalence of the main carbapenemase and extended-spectrum β-lactamases encoding genes in P. aeruginosa clinical isolates. In the present study, we collected 85 P. aeruginosa clinical isolates from different wards of three military hospitals in Tehran, Iran. We used disk diffusion and agar dilution methods to determine resistance to 12 different antibiotics in these isolates. Also, we assessed the blaIMP, blaVIM, blaSHV, blaTEM, and blaCTX genes by polymerase chain reaction methods among all isolates. Our results revealed that all isolates were resistant to two antibiotics, and 76 (89.4%) of isolates were multidrug-resistant. We observed maximum and minimum resistance rates against ticarcillin (n = 77; 90.5%) and colistin (n = 7; 8.2%), respectively. The blaVIM, blaIPM, blaTEM, blaSHV, and blaCTX genes were harbored by 44 (51.8%), 20 (23.5%), 41 (48.2%), 24 (28.2%), and 16 (18.8%) isolates, respectively. The resistance rate among P. aeruginosa strains is significantly increasing that causes nosocomial infections due to different mechanisms, including the high frequency of metallo- β-lactamases and extended-spectrum β-lactamases genes.