title: Nitrofurantoin retains antimicrobial activity against multidrug-resistant urinary Escherichia coli from US outpatients.
abstract: OBJECTIVE
  To examine the prevalence of multidrug-resistant (MDR) urinary Escherichia coli among US outpatients and to assess the antimicrobial activity of oral antibiotics commonly used to treat urinary tract infections (UTIs) against MDR isolates.
  
  
  METHODS
  Antimicrobial susceptibility testing data from outpatient urine cultures in The Surveillance Network (TSN) Database USA were analysed. Six antimicrobial agents from six separate drug classes were included: ampicillin, cefalotin, ciprofloxacin, nitrofurantoin, trimethoprim/sulfamethoxazole and amoxicillin/clavulanate. Isolates were categorized as resistant to one, two, three, four, five and six agents and compared for the years 2001 and 2010. Phenotypes of MDR isolates were assessed to determine antimicrobial activity of recommended therapy for UTIs.
  
  
  RESULTS
  Prevalence of MDR E. coli increased from 9.1% in 2001 (n = 29,198) to 17.0% in 2010 (n = 32,742) (P < 0.0001). In isolates that demonstrated resistance to three, four or five antimicrobial agents in 2010, resistance to nitrofurantoin was observed in only 2.1%, 7.5% and 24.1% of isolates, respectively. Conversely, widespread resistance was observed for trimethoprim/sulfamethoxazole (62.6%, 88.6% and 97.9% for isolates resistant to three, four and five agents, respectively) and ciprofloxacin (48.9%, 84.3% and 98.2% for isolates resistant to three, four and five agents, respectively).
  
  
  CONCLUSIONS
  Because of its consistent antimicrobial activity against MDR E. coli, nitrofurantoin remains a reliable first-line agent for the empirical treatment of acute uncomplicated cystitis.
authors: School of Public Health and Health Services, The George Washington University, Washington, DC, USA School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA.
authors: G V
authors: GV
authors: Sanchez
authors: School of Public Health and Health Services, The George Washington University, Washington, DC, USA School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA.
authors: A M G
authors: AM
authors: Baird
authors: Department of Medical Microbiology and Infectious Diseases, Faculty of Medicine, University of Manitoba, Winnipeg R3E 0J9, Canada.
authors: J A
authors: JA
authors: Karlowsky
authors: Quest Diagnostics Nichols Institute, Chantilly, VA, USA.
authors: R N
authors: RN
authors: Master
authors: Section of Infectious Diseases, Providence Hospital, Washington, DC, USA jbordon@provhosp.org.
authors: J M
authors: JM
authors: Bordon
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D009582:Nitrofurantoin / Q000494:pharmacology*; D010045:Outpatients; D014481:United States; D014552:Urinary Tract Infections / Q000382:microbiology*
chemical_list: D000900:Anti-Bacterial Agents; D009582:Nitrofurantoin
keywords: antibiotic resistance; ciprofloxacin; community; guidelines; primary care; sulphonamides; urinary tract infections