Metallo‑β‑lactamase‑mediated resistance among clinical carbapenem‑resistant Pseudomonas aeruginosa isolates in northern Iran: A potential threat to clinical therapeutics

Objective: Carbapenems are effective agents to treat multidrug‑resistant (MDR) strains of bacteria, including Pseudomonas aeruginosa. However, there is a potential threat of emergence of carbapenem‑resistant P. aeruginosa (CRPA). The aim of this study was to determine antibiotic susceptibility patterns and metallo‑beta‑lactamase (MBL)‑mediated resistance in clinical P. aeruginosa isolates. Materials and Methods: Different clinical specimens were subjected to conventional culture‑based identification of P. aeruginosa. Antimicrobial susceptibility patterns and MBL production were evaluated using the Kirby‑Bauer and combined double‑disk synergy test methods, respectively. Multiplex polymerase chain reaction was performed to investigate the presence of the blaIMP, blaVIM, blaNDM, blaSPM, and blaSIM genes. Results: A total of 71 clinical P. aeruginosa isolates were recovered, of which 28.17 were identified as CRPA. The most active antibiotics were colistin and polymyxin B (92.96 susceptibility to each). A total of 35 and 50 of CRPA isolates were MDR and extensively drug‑resistant (XDR), respectively. MBL activity was shown in 20 of CRPA. A total of 90, 40, and 5 of CRPA isolates harbored the blaIMP, blaVIM, and blaNDM genes, respectively. No correlation was found between the MBL‑encoding genes of P. aeruginosa and patient characteristics. Conclusion: Although the prevalence of CRPA in our therapeutic centers was relatively low, this rate of carbapenem resistance reflects a threat limiting treatment choices. A high prevalence of MDR/XDR phenotypes among the MBL‑producer isolates suggests the need for continuous assessment of antimicrobial susceptibility and surveillance of antibiotic prescription. In addition, infection control measures are needed to prevent further dissemination of these organisms. © 2018 Tzu Chi Medical Journal | Published by Wolters Kluwer - Medknow