Detection of Metallo-β-Lactamases and Klebsiella pneumonia Carbapenemases in Pseudomonas aeruginosa Isolates From Cystic Fibrosis Patients

Background: Respiratory infections caused by Pseudomonas aeruginosa play an important role in the pathogenesis of cystic fibrosis (CF). Objectives: The aim of this study was the detection of metallo-β-lactamases (MBLs) and Klebsiella pneumonia carbapenemases (KPCs) among P. aeruginosa isolates from children with CF in Mofid Children’s Hospital, Tehran, Iran during 2012 - 2013. Patients and Methods: This descriptive study consisted of CF patients who were referred to Mofid Children’s hospital of Tehran during 2012 - 2013. Sputum was collected from the CF patients in sterile containers and tested as early as possible. P. aeruginosa was isolated using standard bacteriologic methods. Antimicrobial susceptibility testing was performed by the disc diffusion method based on the guidelines of the clinical laboratory standards institute (CLSI). Screening of MBLs and KPC production was done using the combination disk diffusion test (CDDT) and modified hodge Test (MHT), respectively. The frequency of imipenemases (IMPs), Verona integron-encoded metallo-β-lactamases (VIMs), and KPC-type genes was detected by PCR and further sequencing methods. Results: Using the DDST, 43.3% of P. aeruginosa isolates were positive for the production of MBLs. In contrast, KPC was not identified in these isolates. IMP, VIM, and KPC genes were detected in 2 (6.66 %), 2 (6.66%), and 0 (0%), respectively. Conclusions: The incidence of MBLs producing P. aeruginosa in patients with CF was not low. The findings indicate that the identification of drug-resistance patterns in P. aeruginosa and the detection of MBL-producing isolates are important in the prevention and control of infections.