Diagn Microbiol Infect Dis

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.K24 AI080942/AI/NIAID NIH HHS/United StatesImNIH/Intramural NIH HHS/United StatesU54CK000163/ACL/ACL HHS/United StatesRS1/CCR320627-01/RS/DRS NIH HHS/United StatesU54-CK000163/CK/NCEZID CDC HHS/United States2014-08-01T00:00:00Z23719087PMC37251938873vault:210