Clinical and molecular correlates of Escherichia coli bloodstream infection from two geographically diverse centers in Rochester, Minnesota and Singapore [PublishAheadOfPrint]

Escherichia coli bacteremia is caused mainly by sequence type complex (STc) 131 and two clades within its fluoroquinolone resistance-associated H30 subclone, H30R1 and H30Rx. We examined clinical and molecular correlates of E. coli bacteremia in two geographically distinct centers. We retrospectively studied 251 unique E. coli bloodstream isolates from 246 patients (48 from the Mayo Clinic, Rochester, Minnesota [MN], 198 from Tan Tock Seng Hospital, Singapore [SG]), from October 2013 through March 2014. Isolates underwent PCR for phylogroup, STc, bla_CTX-M type, and virulence gene profiles, and medical records reviewed. Although STc131 accounted for 25-27% of all E. coli bacteremia isolates at each site, its extended-spectrum β-lactamase-associated H30Rx clade was more prominent in SG than MN (15% versus 4%, P = 0.04). In SG only, patients with STc131 (versus other E. coli) were more likely to receive inactive initial antibiotics (odds ratio [OR] 2.8, P = 0.005); this was true specifically for patients with H30Rx (OR 7.0, P = 0.005). H30Rx comprised 16% of community-onset bacteremia episodes in SG, but none in MN. In SG, virulence scores were higher for H30Rx, as compared to H30R1, non-H30 STc131, and non-STc131 isolates (P < 0.02, all comparisons). At neither site did mortality differ by clonal status. The ESBL-associated H30Rx clade was more prevalent and more often of community-onset in SG, where it predicted inactive empiric treatment. Clonal distribution varies geographically and has potentially important clinical implications. Rapid susceptibility testing and clonal diagnostics for H30/H30Rx might facilitate earlier prescribing of active therapy.

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