BACKGROUND: The prevalence of fecal colonization with Escherichia coli that has reduced susceptibility to fluoroquinolones is unknown. A detailed characterization of such isolates is limited. METHODS: We conducted 3 annual fecal surveillance initiatives at 2 hospitals from 2002 to 2004. All E. coli isolates with reduced susceptibility to fluoroquinolones (minimum inhibitory concentration [MIC] to levofloxacin, > or = 0.125 microg/mL) were identified. We characterized gyrA and parC mutations and organic solvent tolerance (OST). Isolates were compared using pulsed-field gel electrophoresis. RESULTS: Of 789 fecal samples, 149 (18.9%) revealed E. coli with reduced susceptibility to fluoroquinolones. Of 149 isolates, 102 (68.5%) had a MIC > or = 8 microg/mL, 138 (92.6%) had > or = 1 gyrA mutation, 101 (67.8%) had > or = 1 parC mutation, and 59 (39.6%) demonstrated OST. Isolates with a MIC > or = 8 versus <8 microg/mL had more target mutations (median, 3 vs. 1; P<.001) and more often exhibited OST (51% vs. 15%; P<.001). Of 149 isolates, 144 (96.6%) demonstrated a MIC > or = 16 microg/mL to nalidixic acid. The prevalence of OST differed across study years (P = .01). There was no clonal spread of isolates. CONCLUSIONS: Colonization by E. coli with reduced fluoroquinolone susceptibility is common, and fluoroquinolone-resistance characteristics differ significantly over time. Resistance to nalidixic acid may be useful in the identification of E. coli with early resistance mutations.
BACKGROUND: The prevalence of fecal colonization with Escherichia coli that has reduced susceptibility to fluoroquinolones is unknown. A detailed characterization of such isolates is limited. METHODS: We conducted 3 annual fecal surveillance initiatives at 2 hospitals from 2002 to 2004. All E. coli isolates with reduced susceptibility to fluoroquinolones (minimum inhibitory concentration [MIC] to levofloxacin, > or = 0.125 microg/mL) were identified. We characterized gyrA and parC mutations and organic solvent tolerance (OST). Isolates were compared using pulsed-field gel electrophoresis. RESULTS: Of 789 fecal samples, 149 (18.9%) revealed E. coli with reduced susceptibility to fluoroquinolones. Of 149 isolates, 102 (68.5%) had a MIC > or = 8 microg/mL, 138 (92.6%) had > or = 1 gyrA mutation, 101 (67.8%) had > or = 1 parC mutation, and 59 (39.6%) demonstrated OST. Isolates with a MIC > or = 8 versus <8 microg/mL had more target mutations (median, 3 vs. 1; P<.001) and more often exhibited OST (51% vs. 15%; P<.001). Of 149 isolates, 144 (96.6%) demonstrated a MIC > or = 16 microg/mL to nalidixic acid. The prevalence of OST differed across study years (P = .01). There was no clonal spread of isolates. CONCLUSIONS: Colonization by E. coli with reduced fluoroquinolone susceptibility is common, and fluoroquinolone-resistance characteristics differ significantly over time. Resistance to nalidixic acid may be useful in the identification of E. coli with early resistance mutations.
Authors: Jennifer H Han; Warren B Bilker; Irving Nachamkin; Pam Tolomeo; Xiangqun Mao; Neil O Fishman; Ebbing Lautenbach Journal: Infect Control Hosp Epidemiol Date: 2013-08-23 Impact factor: 3.254
Authors: M Kresken; K Becker; H Seifert; E Leitner; B Körber-Irrgang; C von Eiff; P-A Löschmann Journal: Eur J Clin Microbiol Infect Dis Date: 2011-02-24 Impact factor: 3.267
Authors: Ebbing Lautenbach; Joshua P Metlay; Mark G Weiner; Warren B Bilker; Pam Tolomeo; Xiangqun Mao; Irving Nachamkin; Neil O Fishman Journal: Infect Control Hosp Epidemiol Date: 2009-01 Impact factor: 3.254