Detection of class 1, 2, and 3 integrons among Klebsiella pneumoniae isolated from children in Tehran hospitals

Abstract

Background: CTX-M-type β-lactamases are increasingly becoming the predominant ESBLs globally in recent years. Integrons are genetic elements which can integrate gene cassettes, usually antibiotic resistance genes. Objectives: The aims were to determine antibiotic susceptibility and to detect genes encoding CTX-M-1 group enzymes and class 1, 2, and 3 integrons among the Klebsiella pneumoniae isolated from children in Tehran hospitals, Iran. Patients and Methods: Thirty-one K. pneumoniae isolates were collected from samples of children aged 0–12 years admitted to three hospitals in Tehran between May and December 2011, and identified using biochemical tests and PCR. Susceptibility of isolates to 14 antibiotic disks was determined using disk diffusion method. The combined disk method was used for the detection of ESBL. The presence of blaCTX-M-1 group and class 1, 2, and 3 integrons was investigated by PCR. Results: Most of the isolates showed high level of resistance: 17 isolates were simultaneously resistant to Amoxicillin-Clavulanic acid, Cefotaxime, Ceftriaxone, Aztreonam, and Ceftazidime (17/31, 54.9%). All were susceptible to Imipenem and Ciprofloxacin. ESBL production was detected in 54.9% (17/31). The blaCTX-M-1 group was detected in all Cefotaxime-resistant isolates (17/31, 54.9%). Class 1 integron was detected in 8 isolates (25.8%). The class 2 and 3 integrons were not detected. Conclusions: The results showed that the CTX-M-1- producing K. pneumoniae is already present in some parts of Tehran. The presence of class I integron genes among resistant strains of K. pneumoniae highlights the continued monitoring of drug resistance in clinical settings.