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