title: Temporal changes in resistance mechanisms in colonizing Escherichia coli isolates with reduced susceptibility to fluoroquinolones.
abstract: The objective of this study was to characterize the temporal variability of fluoroquinolone resistance mechanisms among Escherichia coli colonizing the gastrointestinal tract of hospitalized patients. Patients with new fluoroquinolone-resistant E. coli (FQREC) colonization were followed with serial fecal sampling until discharge or death. Genetic mechanism(s) of resistance for all FQREC isolates was characterized, including mutations in gyrA and parC and efflux pump overexpression. Of 451 subjects, 73 (16.2%) became newly colonized with FQREC. There was significant variability in regard to temporal changes in resistance mechanisms and levofloxacin MICs among isolates from individual patients. Compared to patients with transient colonization, patients with persistent colonization were more likely to have a urinary catheter (P = 0.04), diarrhea (P = 0.04), and a longer duration of hospitalization (22 and 9.0 mean days, respectively; P = 0.01) prior to sampling. Our data demonstrate the significant variability of resistance mechanisms in colonizing E. coli isolates among hospitalized patients.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. jennifer.han@uphs.upenn.edu
authors.forename: Jennifer H
authors.initials: JH
authors.lastname: Han
authors.forename: Irving
authors.initials: I
authors.lastname: Nachamkin
authors.forename: Pam
authors.initials: P
authors.lastname: Tolomeo
authors.forename: Xiangqun
authors.initials: X
authors.lastname: Mao
authors.forename: Warren B
authors.initials: WB
authors.lastname: Bilker
authors.forename: Ebbing
authors.initials: E
authors.lastname: Lautenbach
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D027081:DNA Gyrase / Q000235:genetics / Q000378:metabolism; D027101:DNA Topoisomerase IV / Q000235:genetics / Q000378:metabolism; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005260:Female; D024841:Fluoroquinolones / Q000494:pharmacology*; D041981:Gastrointestinal Tract / Q000382:microbiology; D006760:Hospitalization; D006801:Humans; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009154:Mutation; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D024841:Fluoroquinolones; D026901:Membrane Transport Proteins; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase
keywords: Escherichia coli; Fluoroquinolones; Resistance