1436. Population-based study of extraintestinal E. coli clonal distribution reveals dominance of sequence type ST131 in Olmsted County, MN
Session: Poster Abstract Session: Epidemiology of Multiple Drug-Resistant Gram Negative Rods
Saturday, October 20, 2012
Room: SDCC Poster Hall F-H
Background:

Most studies of the population structure of extraintestinal E. coli have focused on antimicrobial-resistant isolates or those from select patient groups. The clonal structure of extraintestinal E. coliacross an unselected population is not well described. 

Methods:

Using a newly described clonal typing strategy based on sequencing of fumC and fimH (i.e., CH typing), we inferred multi-locus sequence types (STs) for 299 consecutive, non-duplicate extraintestinal E. coliisolates from all cultures submitted to Olmsted County laboratories in February and March, 2011.  ST131 status was confirmed using single nucleotide polymorphism PCR.  Associated clinical data were abstracted through chart review. 

Results:

Most isolates were from urine (90%), outpatients (68%), and community-onset infections (61%). Overall, 47 different STs were identified.  The most common STs represented well-known pathogenic lineages, including ST131 (27%), ST95 (11%), ST73 (8%), ST127 (6%), and ST69 (5%). 

ST131 was the dominant ST regardless of age or community vs. hospital onset. ST131's prevalence increased progressively with age cohort, i.e., 17% (<18 years), 16% (18-64), 40% (65-80), and 45% (>80).  ST131 accounted for a large proportion of isolates with resistance to fluoroquinolones (81%), trimethoprim-sulfamethoxazole (42%), and gentamicin (79%); a greater share of healthcare-associated (49%) than community-associated (16%) isolates; and fully 76% of E. coli isolates from long-term care facility (LTCF) residents.  Multivariable predictors of ST131 included older age, LTCF residence, prior urinary tract infection, infections requiring hospitalization, and prior antibiotic use.   Patients with ST131 (vs. with other STs) had lower cure rate (73% vs. 89%, p = 0.004), and higher relapse rate (29% vs. 11%, p = 0.001). 

Conclusion:

Analysis of the clonal structure of an unbiased population of extraintestinal E. coli isolates identified ST131 as a predominant, antimicrobial-resistant clonal group associated with healthcare, elderly hosts, and poor outcomes.

Ritu Banerjee, MD, PhD, Division of Pediatric Infectious Diseases, Mayo Clinic, Rochester, MN, Brian Johnston, PhD, Veterans Affairs Medical Center and University of Minnesota, Minneapolis, MN, Christine Lohse, Mayo Clinic , Rochester , MN, Veronika Tchesnokova, University of Washington, Seattle, WA and James R. Johnson, MD, University of Minnesota, Minneapolis, MN

Disclosures:

R. Banerjee, None

B. Johnston, None

C. Lohse, None

V. Tchesnokova, None

J. R. Johnson, Merck: Investigator, Research support
Rochester Medical: Investigator, Research support
Syntiron: Investigator, Research support

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