Evaluation Frequency of Metallo-β-Lactamases and Carbapenemase Enzymes in Pseudomonas aeruginosa Clinical Isolates

Abstract

Background and Objective: Due to the increased prevalence of antibiotic resistance to beta-lactam and carbapenem compounds, the identification of beta-lactamase-producing enzymes is essential for the timely treatment of such isolates. In this regard, the present study aimed to determine the prevalence of metallo-β-lactamases and Klebsiella pneumonia carbapenemase genes among the clinical isolates of Pseudomonas aeruginosa (P. aeruginosa). Materials and Methods: In this cross-sectional descriptive study, a total of 97 clinical isolates were collected from the hospitalized patients of Hamadan hospitals, Hamadan, Iran, within November 2017 to May 2018. After the confirmation of the isolated strains, antibiotic susceptibility of the isolates was determined by disk diffusion agar. Minimum inhibitory concentration (MIC) was performed for imipenem using the Etest method, Combined Double-Disk Test (CDDT), and Modified Hodge test (MHT). In addition, the identification of carbapenemase genes was conducted by polymerase chain reaction (PCR). Results: The obtained results of statistical analysis showed that the highest antibiotic resistance was reported to cefoxitin for 92 (94.8%) isolates, and the lowest antibiotic resistance was observed to piperacillin-tazobactam in 38 (39.2%) isolates. Among the carbapenem antibiotics, the highest antibiotic resistance was reported to imipenem for 48 (49.4%) isolates. Out of 49 (50.51%) carbapenem-resistant isolates, 42 (85.71%) isolates had positive results for MIC. Moreover, 26 (53.06%) and 25 (51.02%) isolates had positive results for IMP/EDTA (CDDT) and MHT test, respectively. The findings of PCR also showed that the highest and lowest gene presence among resistant isolates was related to IMP 20 (40.8%) and GIM gene 6 (12.24%), respectively. Conclusion: The obtained results of the present study showed that a high percentage of the assessed P. aeruginosa isolates were resistant to carbapenem antibiotics, and a high percentage of carbapenem-resistant isolates produced beta-lactamase genes.