1382. Extent of Intestinal Colonization with E. coli ST131 and Fluoroquinolone (FQ)-resistant E. coli (FQREC) among Veterans and their Household Contacts
Session: Oral Abstract Session: Epidemiology of Resistant Gram Negative Infections
Saturday, October 10, 2015: 11:30 AM
Room: 5--AB

Background: E. coli ST131, currently the leading cause of human FQREC infections globally, is especially prominent among U.S. veterans. The distribution of ST131 and other FQREC as intestinal colonizers among veterans and their household (HH) contacts is undefined.

Methods: Randomly selected Minneapolis VAMC outpatients and inpatients, and any available HH members (humans and pets), were recruited as fecal donors for cross-sectional surveillance for colonization with ST131 and other FQREC. Fecal samples were screened for E. coli and FQREC by selective cultures, and for ST131 by PCR analysis of isolated colonies and population DNA.

Results: The 457 subjects to date included 185 veterans (117 outpatients, 68 inpatients) and 272 HH members (142 humans, 130 animals), and represented 98 multi-subject HHs (370 total subjects) and 87 "veteran-only" HHs. Overall, 31 subjects carried ST131 (22 FQ-resistant [FQ-R], 9 FQ-susceptible [FQ-S]) and 40 carried FQREC (22 ST131, 18 non-ST131). Colonization prevalence declined by host group (inpatients > outpatients > household members > animals) for ST131 overall, FQ-R ST131, and FQREC, but not FQ-S ST131 (Table 1). ST131 accounted for ³ 50% of FQREC within each host group except animals (no ST131). Within the multiple-subject HHs, colonization with ST131 or FQREC clustered by HH, being more likely if another HH member was so colonized than if not (for FQREC, 10/27 [37%] vs. 17/353 [5%]: P < 0.001; for ST131, 8/23 [35%] vs. 16/370 [4%]: P < 0.001).

Table 1. Distribution of E. coli, ST131 (FQ-R and FQ-S), and FQREC by subgroup.

Prevalence of colonization with indicated organism, no. of subjects (column %)


Inpatient (n = 68)

Outpatient (n = 117)

HH membersa (n = 142)

Animals (n = 130)

E. coli

46 (67)

107 (92)

94 (57)

78 (60)

ST131 total

8 (12)

11 (9)

12 (8)


ST131 FQ-R

6 (9)

7 (6)

9 (6)


ST131 FQ-S

2 (3)

4 (3)

3 (2)



11 (17)

12 (10)

16 (11)

3 (2)

aHH members: human household members

Conclusion: Among veterans (especially inpatients) and their HH contacts, colonization with FQ-R ST131 is relatively frequent, and equals or exceeds the frequency of colonization with other FQREC. Within-HH strain sharing is likely. These phenomena may underlie the high burden of ST131 disease among veterans, and may be amenable to preventive interventions.

Muhanad Mohamed, MD1,2, Connie Clabots, BS MT(ASCP)3, Billie C. S. Slater, MA3 and James R. Johnson, MD, FIDSA, FACP, FRCPE3,4, (1)Infectious Diseases, University of Minnesota, Minneapolis, MN, (2)Infectious Diseases, Minneapolis Veterans Affairs Medical Center, Minneapolis, MN, (3)Veterans Affairs Medical Center, Minneapolis, MN, (4)Department of Medicine, Division of Infectious Diseases and International Medicine, University of Minnesota, Minneapolis, MN


M. Mohamed, None

C. Clabots, None

B. C. S. Slater, None

J. R. Johnson, Crucell: Consultant , Consulting fee
ICET: Consultant , Consulting fee
Merk: Investigator , Grant recipient
Tetraphase: Investigator , Grant recipient

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