Risk factors for ambulatory urinary tract infections caused by high-MIC fluoroquinolone-susceptible Escherichia coli in women: results from a large case-control study.

TitleRisk factors for ambulatory urinary tract infections caused by high-MIC fluoroquinolone-susceptible Escherichia coli in women: results from a large case-control study.
Publication TypeJournal Article
Year of Publication2015
AuthorsRattanaumpawan P, Nachamkin I, Bilker WB, Roy JA, Metlay JP, Zaoutis TE, Lautenbach E
Corporate AuthorsCDC Prevention Epicenters Program
JournalJ Antimicrob Chemother
Volume70
Issue5
Pagination1547-51
Date Published2015 May
ISSN1460-2091
Abstract

OBJECTIVES: 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).

PATIENTS AND 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.

DOI10.1093/jac/dku548
Alternate JournalJ. Antimicrob. Chemother.
PubMed ID25630645
PubMed Central IDPMC4398470
Grant ListK24-AI080942 / AI / NIAID NIH HHS / United States
R21-AI103497 / AI / NIAID NIH HHS / United States
U54-CK000163 / CK / NCEZID CDC HHS / United States