Biotech Health Sci. 2014 August; 1(2): e22085. Published online 2014 August 28. Research Article Emergence of OXA-Type Extended-Spectrum β-Lactamases Among Enterobacter cloacae Isolates Collected From Hospitals of Tehran, Karaj and Qazvin, Iran Amir Peymani 1 ; Taghi Naserpour Farivar 1 ; Mahdi Mohammadi Ghanbarlou 1 ; Marzieh Marandi 1 ; Mehdi Sahmani 1 ; Reza Najafipour 1,* 1 Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, IR Iran *Corresponding author: Reza Najafipour, Cellular and Molecular Research Center, Qazvin University of Medical Sciences, Qazvin, IR Iran. Tel/Fax: +98-2813324971, E-mail: rnajafipour@ gmail.com Received: January 10, 2014; Revised: May 12, 2014; Accepted: July 1, 2014 Background: Extended-Spectrum β-Lactamases (ESBLs)-producing Enterobacter cloacae has been increasingly reported as a major clinical concern in recent years. TEM and SHV β-lactamase are the most common ESBL genotypes that are found in Enterobacteriaceae; however, there are also new families of ESBLs, including OXA-type enzymes, which are one of the most important mechanisms of resistance to oxyimino-cephalosporin antibiotics. OXA-type ESBLs are divided into five groups. Objectives: The main aim of the present study was to determine the frequency of bla OXA genes among ESBL-producing E. cloacae isolates in three distinct provinces of Iran. Patients and Methods: A total of 82 non-repetitive ESBL-producing E. cloacae isolates were collected from hospitalized patient in Qazvin, Karaj, and Tehran hospitals, Iran. The isolates were identified by standard laboratory methods and then confirmed by API 20E strips. PCR and sequencing was performed for detection of bla OXA-1 , bla OXA-2 , bla OXA-9 , and bla OXA-10 genes. The clonal relatedness of OXA-producing isolates was assessed by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). Results: In total, 48 ESBL-producing isolates (58.5%) were positive for the bla OXA-1 gene. All bla OXA-1 -producing isolates showed multidrug resistant pattern. In this study, bla OXA-2 , bla OXA-9 , and bla OXA-10 genes were not detected. The ERIC-PCR results showed that 42 OXA- producing isolates (77.7%) were genetically diverse with different band patterns. Conclusions: This study was the first report of the emergence of the plasmid-encoded bla OXA genes among E. cloacae isolates in Iran. These findings highlight the need to use appropriate infection control policy and rational antibiotic therapy to reduce further spread of these resistant bacteria in the studied hospitals. Keywords: Enterobacter cloacae; Extended-Spectrum β-Lactamases; OXA-type β-Lactamase Copyright © 2014, School of Paramedical Sciences, Qazvin University of Medical Sciences. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 1. Background Enterobacter cloacae is the most frequent bacterial that causes nosocomial infections among hospitalized patients (1, 2). This organism can cause several clinical diseases such as bacteremia as well as lower respiratory tract, skin, urinary tract, and soft-tissue infections (2). Risk factors associated with infections with E. cloacae in- clude immunosuppression, long-term hospitalization, and invasive procedures or surgeries (3). Infection with E. cloacae is associated with increased morbidity and mortality in hospitalized patients, especially in inten- sive care units (ICUs) and other high-risk hospital set- tings (4). Beta-lactam compounds are important group of prescribed antibiotics for treatment of patients in- fected with E. cloacae (2); however, extensive and inap- propriate use of broad-spectrum β-lactam antibiotics lead to appearance of multidrug resistant E. cloacae isolates, which severely limit the therapeutic options for treatment of infected patients. Although resistance of Enterobacter species to third-generation cephalo- sporins is most typically caused by overproduction of AmpC β-lactamases, the role of extended-spectrum β-Lactamases (ESBLs) has been increasingly reported among Enterobacteriaceae (5). ESBLs have been found mostly in Klebsiella species and Escherichia coli but have also been described in other Enterobacteriaceae includ- ing Enterobacter, Citrobacter, and Serratia species. ESBLs are the most important mechanisms of resistance to third-generation cephalosporins with remarkable abil- ity to develop resistance to several classes of antimicro- bial agents (6). These enzymes have been commonly lo- cated on plasmids that are transferable from strain to strain and between bacterial species. TEM and SHV are the most common types of ESBLs among E. cloacae (7); however, a number of different ESBL types have been recently identified in Enterobacter species such as CTX- M and OXA (8). There are five groups of OXA-type ESBLs.