Determination of Pseudomonas Aeruginos Producing Metallo-Beta-Lactamases Isolated from Clinical Specimens by Imipenem-EDTA Combined Disk Method in Ahwaz, Iran

Background and Objective: Pseudomonas aeruginosa is a causative agent of nosocomial infections. Metallo-beta-lactamases (MBLs) are considered among the most crucial resistant agents of Pseudomonas aeruginosa to carbapenem. Because of the important role of carbapenemes in the treatment of Pseudomonas infections, in this study, the Pseudomonas aeruginosa producing metallo-beta-lactamases were investigated. Materials and Methods: A total of ۲۳۶ Pseudomonas aeruginosa were examined. These isolates were collected from hospitalized patients’ clinical specimens in Imam Khomeini and Golestan hospitals of Ahvaz, Iran. After identification of the isolates by standard biochemical tests, their antimicrobial resistant patterns to ۱۰ common antibiotics were determined based on CLSI protocol by disk diffusion agar method. Finally, the metallo-beta-lactamase production by Pseudomonas aeruginosa isolates was identified by Imipenem-EDTA combined disk method. Results: Of ۲۳۶ Pseudomonas aeruginosa isolates, ۱۲۲ isolates (۵۱.۴%) were resistent to imipenem. Based on the results of Imipenem-EDTA combined disk method, production of metallo-beta-lactamases was known in ۱۱۰/۱۲۲ (۹۰%) Pseudomonas aeruginosa isolates. Conclusion: Since MBLs producing Pseudomonas aeruginosa are resistant to all other beta-lactam antibiotics, it is vital to screen imipenem non-susceptible isolates of Pseudomonas aeruginosa for MBLs production. This will be effective in the selection of suitable antibiotic and recovery pace of the patients.

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Keywords: Pseudomon asaeruginosa , Imipenem-EDTA combined disk method , Metallo-beta-lactamase