Objectives: Production of metallo-β-lactamases (MBLs) is an important mechanism of resistance to carbapenems. This study aimed to detect the MBL-producing Pseudomonas aeruginosa clinical isolates and to investigate the presence of bla VIM, bla IMP, bla SPM, bla NDM, bla GIM, bla AIM, and bla SIM genes in these isolates in Bushehr, Iran.
Materials and methods: A total of 169 P. aeruginosa clinical isolates were collected from three hospitals in Bushehr. The modified carbapenem inactivation method (mCIM) was used for the phenotypic detection of carbapenemase production. A combination disk test (CDT) was performed for the phenotypic detection of MBL production. To investigate the presence of bla VIM, bla IMP, bla SPM, bla NDM, bla GIM, bla AIM, and bla SIM genes, PCR and sequencing was carried out.
Results: Based on the results of mCIM, 40 (23.7%) of 169 isolates were carbapenemase producers. CDT revealed that 26 (15.4%) isolates were MBL producers. bla IMP, bla NDM, and bla VIM genes were found in 18 (69.2%), 8 (30.8%), and 1 (3.8%) of the MBL-producing isolates, respectively. Coexistence of bla IMP and bla NDM was observed in 2 (7.7%) MBL-producing isolates. Among all 169 P. aeruginosa isolates, 23 (13.6%) harbored bla NDM, 18 (10.6%) carried bla IMP, and 1 (0.6%) carried the bla VIM gene. bla SPM, bla GIM, bla AIM, and bla SIM were not found in the present study.
Conclusion: bla NDM, bla IMP, and bla VIM genes were detected in this study, which could be a warning sign about the prevalence of these genes among P. aeruginosa clinical isolates in our region. Proper monitoring and detection of MBL-producing isolates are essential steps to prevent the spread of these isolates.
Keywords: MBL; Metallo-β-lactamase; Pseudomonas aeruginosa; blaIMP; blaNDM; blaVIM.