Emergence of blaCTX-M-15 Gene and Its Transferability in Enterobacter spp. Isolated From the Hospitals of Tehran, Iran

Abstract

Background: Enterobacter spp. is increasingly recognized as an important nosocomial pathogen and implicated in many episodes of hospital acquired infections. Objectives: The current study aimed to describe distribution and transferability of bla CTX-M-15 gene, and the antibiotic susceptibility pattern in the clinical isolates of Enterobacter spp. Materials and Methods: A total of 110 Enterobacter isolates were collected from five hospitals in Tehran, Iran from May 2012 to April 2013. Enterobacter species were identified by API 20E system. Antibacterial susceptibility was determined by disk diffusion method, and extended spectrum beta lactamase (ESBL) production was confirmed by combined disk method. The bla CTX-M-15 gene was identified by PCR with specific primers. The transferability of the bla CTX-M-15 was tested by conjugation with broth matting method. Results: The prevalence of Enterobacter species was E. cloacae (78.2 %), E. aerogenes (6.13 %) and E. sakazakii (8.2%). They were from different clinical sources. Maximal resistance in Enterobacter isolates was noticed against Augmentin®, trimethoprim -sulfamethoxazole and cefoxitin 75.5%, 64.5%, and 59.1%, respectively. Fourteen isolates, showed ESBL phenotype. The bla CTX-M-15 gene frequency in Enterobacter isolates was 11.8%. Three conjugative plasmids containing bla CTX-M-15 were found in one Enterobacter isolate.