title: Characterization of CTX-M-Type Extend-Spectrum β-Lactamase Producing Klebsiella spp. in Kashan, Iran.
abstract: BACKGROUND
  The CTX-M family consists of more than 50 β-lactamases, which are grouped on the basis of sequences into five subtypes including CTX-M-1, CTX-M-2, CTX-M-8, CTX-M-9 and CTX-M-25.
  
  
  OBJECTIVE
  The current study aimed to detect subtypes of CTX-M extended-spectrum β-lactamases (ESBLs) among ESBL positive Klebsiella isolates from patients in Kashan, Iran.
  
  
  METHODS
  A total of 100 clinical isolates of Klebsiella were collected and the isolates, which showed resistance or reduced susceptibility to cefotaxime, ceftazidime and/or aztreonam by the disk diffusion method were selected. These isolates were identified as ESBL-producing isolates by double disk synergy tests using clavulanic acid, cefotaxime, ceftazidime and aztreonam. The blaCTX-M type determinants were identified by the Polymerase Chain Reaction (PCR) method followed by DNA sequencing.
  
  
  RESULTS
  Of the 100 Klebsiella isolates, 41 (41%) demonstrated resistance or reduced susceptibility to ceftazidime and/or aztreonam and 35% (n = 35) were ESBL-producers. Twenty-eight (8o%) of the ESBL-producing isolates carried the blaCTX-M type genes. Based on PCR assays and sequencing of blaCTX-M genes, CTX-M-1, CTX-M-2 and CTX-M-9 were identified in 21 (60%), 15 (42%) and nine (34%) of these isolates, respectively (GenBank accession numbers KJ803828-KJ803829).
  
  
  CONCLUSIONS
  Our study showed that the frequency of blaCTX-M genes among Klebsiella isolates in our region is at an alarming rate. Also, we found a high prevalence of blaCTX-M-1 β-lactamase in Klebsiella isolates in Kashan.
authors.affiliation: Department of Infectious Diseases, School of Medicine, Kashan University of Medical Sciences, Kashan, IR Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Afzali
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Kashan University of Medical Sciences, Kashan, IR Iran.
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Firoozeh
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Kashan University of Medical Sciences, Kashan, IR Iran.
authors.forename: Atena
authors.initials: A
authors.lastname: Amiri
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, Kashan University of Medical Sciences, Kashan, IR Iran.
authors.forename: Rezvan
authors.initials: R
authors.lastname: Moniri
authors.affiliation: Department of Parasitology and Mycology, School of Medicine, Alborz University of Medical Sciences, Karaj, IR Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Zibaei
keywords: Antibiotic Resistance; Blactx-M; Clinical Specimens; ESBLs; Klebsiella spp.