372. Molecular characterization of fecal Escherichia coli isolates from households (HHs) of veterans within which one or more HH members carries E. coli sequence type 131 (ST131) or other fluoroquinolone (FQ)-resistant E. coli (FQREC)
Session: Poster Abstract Session: HAI: Multi Drug Resistant Gram Negatives
Thursday, October 27, 2016
Room: Poster Hall
  • IDWeek_CVAST_2016_Poster.Muhanad.Final.pdf (6.1 MB)
  • Background: Among veterans, FQREC infections are a significant problem and are caused mainly by E. coli ST131, a recently emerged disseminated clonal group. Infecting FQREC strains emerge from the host's gut reservoir. The molecular characteristics of colonizing ST131 strains and other FQREC among veterans and their HH contacts may determine which strains persist or cause infection, but as yet are undefined.

    Methods: Fecal surveillance of 290 randomly selected veterans and their 300 HH members (including 143 pets) showed that 81 subjects (of 590 total) from 290 households carried ST131 and/or FQREC. Fecal E. coli from households with at least one ST131 and/or FQREC-colonized member were characterized molecularly. Ten E. coli colonies per sample underwent PCR-based clonal screening. One isolate per clone underwent phylotyping, virulence genotyping, sequence type (ST) determination, and pulsotyping.

    Results: The 590 total subjects yielded 501 unique (by clone and subject) fecal E. coli isolate. Of these, 61 were FQREC (of which 30 [49%] were ST131 and 49 were ST131 (of which 30 [61%] were FQREC); 210 were from the 86 HHs with at least one ST131 and/or FQREC-colonized member. These 210 E. coli isolates (149 FQ-susceptible [FQ-S], 61 FQREC) included 7 of the 8 E. coli phylogroups (% of 210): B2 (45%), D (17%), B1 (16%), A (12%), F (6%), E (4%), and C (0.5%). Compared with FQ-S isolates, FQREC isolates were more often from group B2 (61% vs. 38%: P = .003) and had numerically higher virulence gene (VG) scores (median, 10 [range 1-14] vs. 6 [1-19]). The 49 ST131 isolates had significantly higher VG scores than the 161 non-ST131 isolates overall (median, 12 [6-20] vs. 6 [1-19]: P < 0.001) or the 31 non-ST131 FQREC (7 [1-12]: P < 0.001). The 30 FQREC ST131 isolates had slightly but significantly lower VG scores than the 14 FQS ST131 isolates (median, 12 [6-14] vs. 13 [11-20]: P < 0.001). Overall, ST131 was the most prevalent defined ST (23%), followed by ST73 and ST141 (5% each). Virulence-associated pulsotype 968 accounted for 33% of FQREC ST131 isolates.

    Conclusion: Among veterans and their HH contacts ST131 is the single most common cause of FQREC colonization. Colonizing ST131 FQREC strains exhibit extensive VG profiles and represent classic pathogenic pulsotypes. Such colonization likely contributes to the high burden of ST131 disease among veterans, and may be amenable to preventive interventions.

    Muhanad Mohamed, MD, Infectious Diseases, University of Minnesota, Minneapolis, MN, Connie Clabots, BS MT(ASCP), Minneapolis Veterans Affairs Medical Center, Minneapolis, MN, Stephen B. Porter, MS, University of Minnesota, Minneapolis, MN and James R. Johnson, MD, FIDSA, FACP, FRCPE, Department of Medicine, Division of Infectious Diseases and International Medicine, University of Minnesota, Minneapolis, MN


    M. Mohamed, None

    C. Clabots, None

    S. B. Porter, None

    J. R. Johnson, None

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