title: Risk factors for ambulatory urinary tract infections caused by high-MIC fluoroquinolone-susceptible Escherichia coli in women: results from a large case-control study.
abstract: OBJECTIVE
  The prevalence of high-MIC fluoroquinolone-susceptible Escherichia coli (FQSEC) has been increasing. These isolates are one step closer to full fluoroquinolone (FQ) resistance and may lead to delayed response to FQ therapy. Our study aimed to investigate the epidemiology of high-MIC FQSEC in ambulatory urinary tract infections (UTIs).
  
  
  METHODS
  A case-control study was conducted at outpatient services within the University of Pennsylvania Health System, Philadelphia. All female subjects with non-recurrent UTI caused by FQSEC (levofloxacin MIC < 4 mg/L) were enrolled. Cases were subjects with high-MIC FQSEC UTI (levofloxacin MIC >0.12 but < 4 mg/L) and controls were subjects with low-MIC FQSEC UTI (levofloxacin MIC ≤0.12 mg/L). Data on microbiology results and baseline characteristics were extracted from electronic medical records.
  
  
  RESULTS
  During the 3 year study period (May 2008-April 2011), 11 287 episodes of E. coli bacteriuria were identified. The prevalence of FQSEC, FQ-intermediate susceptible E. coli and FQ-resistant E. coli was 75.0%, 0.4% and 24.6%, respectively. A total of 2001 female subjects with FQSEC UTI were enrolled into our study (165 cases and 1836 controls). Independent risk factors for high-MIC FQ susceptibility included Asian race (OR = 2.92; 95% CI = 1.29-6.58; P = 0.02), underlying renal disease (OR = 2.18; 95% CI = 1.15-4.14; P = 0.02) and previous nitrofurantoin exposure (OR = 8.86; 95% CI = 1.95-40.29; P = 0.005).
  
  
  CONCLUSIONS
  Asian race, underlying renal disease and previous exposure to nitrofurantoin were identified as independent risk factors for high-MIC FQSEC. There may be some factors that are more common in Asians, which may result in the selection of high-MIC FQSEC. Further studies are necessary to explore these findings.
authors: Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, PA, USA Division of Infectious Diseases and Tropical Medicine, Department of Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand pinyo@mail.med.upenn.edu.
authors: Pinyo
authors: P
authors: Rattanaumpawan
authors: Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors: Irving
authors: I
authors: Nachamkin
authors: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, USA.
authors: Warren B
authors: WB
authors: Bilker
authors: Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, USA.
authors: Jason A
authors: JA
authors: Roy
authors: Division of General Internal Medicine, Massachusetts General Hospital, Boston, MA, USA.
authors: Joshua P
authors: JP
authors: Metlay
authors: Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, PA, USA.
authors: Theoklis E
authors: TE
authors: Zaoutis
authors: Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, PA, USA Division of Infectious Diseases, Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
authors: Ebbing
authors: E
authors: Lautenbach
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000553:Ambulatory Care; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D016022:Case-Control Studies; D004926:Escherichia coli / Q000187:drug effects / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000453:epidemiology*; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D006801:Humans; D015994:Incidence; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015143:Philadelphia / Q000453:epidemiology; D012307:Risk Factors; D014552:Urinary Tract Infections / Q000453:epidemiology*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones
keywords: Escherichia coli; UTIs; fluoroquinolone resistance
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