title: Phenotypic Characterization of Multidrug-resistant Escherichia Coli with Special Reference to Extended-spectrum-beta-lactamases and Metallo-beta-lactamases in a Tertiary Care Center.
abstract: BACKGROUND
  The increasing reports on extended-spectrum-beta-lactamase and metallo-beta-lactamase producing Escherichia coli have addressed a potential threat to global health since it is found to be highly resistance to most of the currently available antibiotics including carbapenems. The present study was aimed to determine the antibiogram of extended-spectrum-beta-lactamase and metallo-beta-lactamase producing MDR E. coli isolates from various clinical samples.
  
  
  METHODS
  This was a cross-sectional study conducted over a period of seven months from December 2013 to July 2014 at bacteriology laboratory of Tribhuvan University Teaching Hospital. A total of 250 clinical specimens (urine, pus, sputum, blood, body fluid, bile, tissue and central venous pressure line tip) were processed from inpatients, with multidrug-resistant Escherichia coli infections. Standard microbiological techniques were used for isolation and identification of the isolates. The presence of extended-spectrum-beta-lactamase was detected by phenotypic confirmatory test recommended by Clinical and Laboratory Standards Institute and imipenem (IMP) /EDTA combined disc method was performed to detect metallo-beta-lactamase mediated resistance mechanism.
  
  
  RESULTS
  We found high level of beta lactamase mediated resistance mechanism as part of multidrug resistance. Among 250 MDR isolates, 60% isolates were extended-spectrum-beta-lactamase producers and 17.2% isolates were metallo-beta-lactamase producers. Co-existence of extended-spectrum-beta-lactamase and metallo-beta-lactamase identified in 6.8% isolates.
  
  
  CONCLUSIONS
  Beta-lactamase mediated resistance mechanisms are accounting very high in the multidrug resistant isolates of E. coli. Therefore, early detection of beta lactamase mediated resistant strains and their current antibiotic susceptibility pattern is necessary to avoid treatment failure and prevent the spread of MDR.
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: B
authors.initials: B
authors.lastname: Shrestha
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: S
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: S K
authors.initials: SK
authors.lastname: Mishra
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: H P
authors.initials: HP
authors.lastname: Kattel
authors.affiliation: Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Tada
authors.affiliation: Department of International Medical Cooperation, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Ohara
authors.affiliation: Department of Infectious Diseases, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kirikae
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: B P
authors.initials: BP
authors.lastname: Rijal
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: J B
authors.initials: JB
authors.lastname: Sherchand
authors.affiliation: Department of Microbiology, Institute of Medicine, Maharajgunj, Kathmandu, Nepal.
authors.forename: B M
authors.initials: BM
authors.lastname: Pokhrel
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D010641:Phenotype; D062606:Tertiary Care Centers; D001618:beta-Lactamases / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001618:beta-Lactamases
keywords: E. coli; extended-spectrum-β-lactamase; metallo-β-lactamase; multidrug-resistance.