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Updated: May 11, 2026

High-throughput Screening of Chemical Compounds to Elucidate Their Effects on Bacterial Persistence
Published on: February 23, 2021
Temporal changes in resistance mechanisms in colonizing Escherichia coli isolates with reduced susceptibility to
Jennifer H Han1, Irving Nachamkin, Pam Tolomeo
1Division of Infectious Diseases, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. jennifer.han@uphs.upenn.edu
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.
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