title: The distribution of beta lactamase genes in Escherichia coli phylotypes isolated from diarrhea and UTI cases in northwest Iran.
abstract: BACKGROUND
  Pathogenic Escherichia coli strains are a common cause of intestinal and extra-intestinal infections, especially in developing countries. Extended spectrum beta-lactamases (ESBLS), a heterogeneous group of plasmid-encoded beta-lactamases, are common throughout the world.
  
  
  OBJECTIVE
  The aim of the present study was to determine the phenotypic and genotypic characteristics of ESBLS produced by E. coli isolates taken from patients with diarrhea and urinary tract infections (UTI) in northwest Iran.
  
  
  METHODS
  A total of 132 E. coli isolates (92 isolates from UTI and 40 isolates from diarrheic cases) were recovered and confirmed by biochemical tests. The isolates were examined for blaTEM and blaSHV genes and phylogenetic background by two multiplex PCR assays. The isolates were tested for antibiotic susceptibility against nine antibiotic agents by the disk diffusion method.
  
  
  RESULTS
  The phylogenetic analysis showed that the UTI isolates mostly fell into phylo-group B2, followed by D, while the diarrheic isolates belonged to phylo-groups D and A. Out of 92 UTI isolates, 29.3% and 17.4% possessed blaTEM and blaSHV genes, respectively. Ten diarrheic isolates were positive for blaTEM, two isolates possessed the blaSHV gene, and one isolate was positive for both genes. The UTI isolates that were positive for blaTEM and blaSHV genes mostly belonged to phylo-groups D and B2, whereas the diarrhea isolates were in phylo-groups D and A. Phylogenetic group D isolates have an accumulation of ESBLS genes in the diarrheic and UTI isolates. In both the UTI and diarrhea isolates, the maximum rate of resistance was against cefazolin, and the minimum rate of resistance was against nitrofurantoin. Twenty-four antibiotic resistance patterns were observed among the isolates. The amikacin, ciprofloxacin, cefotaxime, cefuroxime, cefazolin, gentamicin, nalidixic acid and trimethoprim/sulfamethoxazole resistance pattern was the most prevalent in the isolates that belonged to phylo-group D.
  
  
  CONCLUSIONS
  The correct choice of effective antibiotic policy is needed to limit the spread of antibiotic resistance in bacteria.
authors.affiliation: Molecular Microbiology Department, Faculty of Veterinary Medicine, Shahid Bahonar University, Kerman, Iran.
authors.forename: Zahra
authors.initials: Z
authors.lastname: Hemati
authors.affiliation: Molecular Microbiology Department, Faculty of Veterinary Medicine, Shahid Bahonar University, Kerman, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Ghanbarpour
authors.affiliation: Department of Microbiology, International Branch, Shahid Beheshti University of Medical Science, Tehran, Iran.
authors.forename: Hesam
authors.initials: H
authors.lastname: Alizade
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003967:Diarrhea / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D014552:Urinary Tract Infections / Q000382:microbiology*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases