title: Antibiotic-resistant Escherichia coli in women with acute cystitis in Canada.
abstract: BACKGROUND
  Trimethoprim-sulfamethoxazole (TMP-SMX) has been a traditional first-line antibiotic treatment for acute cystitis; however, guidelines do not recommend TMP-SMX in regions where Escherichia coli resistance exceeds 20%. While resistance is increasing, there are no recent Canadian estimates from a primary care setting to guide prescribing decisions.
  
  
  METHODS
  A total of 330 family physicians assessed 752 women with suspected acute cystitis between 2009 and 2011. Physicians documented clinical features and collected urine for cultures for 430 (57.2%) women. The proportion of resistant isolates of E coli and exact binomial 95% CIs were estimated nationally, and compared regionally and demographically. These estimates were compared with those from a 2002 national study.
  
  
  RESULTS
  The proportion of TMP-SMX-resistant E coli was 16.0% nationally (95% CI 11.3% to 21.8%). This was not statistically higher than 2002 (10.9% [P=0.14]). TMP-SMX resistance was increased in women ≤50 years of age (21.4%) compared with older women (10.7% [P=0.037]). In women with no antibiotic exposure in the previous three months, TMP-SMX-resistant E coli remained more prevalent in younger women (21.8%) compared with older women (4.4% [P=0.003]). The proportion of ciprofloxacin-resistant E coli was 5.5% nationally (95% CI 2.7% to 9.9%), and was increased compared with 2002 (1.1% [P=0.036]). Ciprofloxacin resistance was highest in British Columbia (17.7%) compared with other regions (2.7% [P=0.003]), and was increased compared with 2002 levels in this province (0.0% [P=0.025]). Nitrofurantoin-resistant E coli levels were low (0.5% [95% CI 0.01% to 2.7%).
  
  
  CONCLUSIONS
  The proportion of TMP-SMX-resistant E coli causing acute cystitis in women in Canada remains below 20% nationally, but may exceed this level in premenopausal women. Ciprofloxacin resistance has increased, notably in British Columbia. Nitrofurantoin resistance levels are low across the country. These observations indicate that TMP-SMX and nitrofurantoin remain appropriate empirical antibiotic agents for treating cystitis in primary care settings in Canada.
authors.affiliation: Granovsky-Gluskin Family Medicine Centre, Ray D Wolfe Department of Family Medicine, Mount Sinai Hospital, University of Toronto, Toronto, Ontario ; Department of Community and Family Medicine, University of Toronto, Toronto, Ontario.
authors.forename: Warren J
authors.initials: WJ
authors.lastname: McIsaac
authors.affiliation: Department of Community and Family Medicine, University of Toronto, Toronto, Ontario.
authors.forename: Rahim
authors.initials: R
authors.lastname: Moineddin
authors.affiliation: Department of Community and Family Medicine, University of Toronto, Toronto, Ontario.
authors.forename: Christopher
authors.initials: C
authors.lastname: Meaney
authors.affiliation: Department of Microbiology, Mount Sinai Hospital and University Health Network, Toronto, Ontario ; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario.
authors.forename: Tony
authors.initials: T
authors.lastname: Mazzulli
keywords: Acute cystitis; Antimicrobial resistance; E coli