title: Determination of susceptibility to fosfomycin and tigecycline of Enterobacteriaceae, particularly Escherichia coli isolates, producing extended-spectrum β-lactamases from multiple regional Canadian hospitals.
abstract: BACKGROUND
  The worldwide spread of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae, particularly Escherichia coli, has significantly limited therapeutic options, especially for urinary tract infections. Although limited in their indications, fosfomycin and tigecycline are potential agents to treat infections due to ESBL-producing organisms. Although not routinely performed, susceptibility testing to both is necessary to ensure there is not an increase in resistance.
  
  
  METHODS
  A total of 160 isolates of ESBL-producing E coli were isolated from patients at multiple regional hospitals in the Interior Health Region of British Columbia from June 2009 to January 2012. Isolates were obtained from various body fluids and sites including urine (78.2%), wounds, blood, gall bladder drain and respiratory specimens. All isolates were tested using the E-test method (Etest, bioMérieux, France) for tigecycline and Kirby Bauer disk diffusion method for fosfomycin using European Committee of Antimicrobial Susceptibility Testing breakpoints for tigecycline and Clinical and Laboratory Standards Institute zone sizes for fosfomycin.
  
  
  RESULTS
  All 160 isolates were found to be susceptible to tigecycline, while five isolates (3.1%) were resistant to fosfomycin (four resistant, one intermediate).
  
  
  CONCLUSIONS
  Although resistance to these antibiotics has previously been reported, the present study confirmed that isolates of ESBL-producing E coli from the Interior Health Region of British Columbia remain highly susceptible to both tigecycline and fosfomycin.
authors.affiliation: Department of Biological Science, Faculty of Science, Thompson Rivers University;
authors.forename: Carlee
authors.initials: C
authors.lastname: Beuk
authors.affiliation: Department of Pathology & Laboratory Medicine, Kelowna General Hospital, Kelowna, British Columbia.
authors.forename: Christian
authors.initials: C
authors.lastname: Hill
authors.affiliation: Department of Pathology, Royal Inland Hospital, Kamloops;
authors.forename: Sue
authors.initials: S
authors.lastname: Whitehead
authors.affiliation: Department of Pathology & Laboratory Medicine, Kelowna General Hospital, Kelowna, British Columbia.
authors.forename: Edith
authors.initials: E
authors.lastname: Blondel-Hill
authors.affiliation: Department of Biological Science, Faculty of Science, Thompson Rivers University;
authors.forename: Ken
authors.initials: K
authors.lastname: Wagner
authors.affiliation: Department of Biological Science, Faculty of Science, Thompson Rivers University;
authors.forename: Naowarat
authors.initials: N
authors.lastname: Cheeptham
keywords: Antibiotic resistance; Canada; ESBL-producing Enterobacteriaceae; Fosfomycin; Regional hospitals; Southern Interior BC; Tigecycline