Molecular epidemiology of Escherichia coli sequence type 131 and Its H30 and H30-Rx subclones among extended-spectrum-β-lactamase-positive and -negative E. coli clinical isolates from the Chicago Region, 2007 to 2010

Abstract

We assessed Escherichia coli ST131 and its H30 and H30-Rx subclones for virulence genes, antimicrobial resistance, and extended-spectrum beta-lactamase (ESBL) type. Although both subclones were associated with ESBL production, H30-Rx isolates had higher resistance scores and were associated specifically with CTX-M-15. Three virulence genes (iha, sat, and iutA) were more prevalent among H30 than non-H30 ST131 isolates. Thus, the H30 and H30-Rx subclones are more antimicrobial resistant and have virulence profiles that are distinct from those of non-H30 ST131 isolates.

Fig 1

Resistance phenotypes and ESBL types among 71 ST131 isolates. (A) All 71 ST131 isolates, stratified by H30 subclone status. (B) The 62 H30 subclone isolates, stratified by H30-Rx status. ESBL, extended-spectrum β-lactamase; FQ-R, fluoroquinolone resistant. Prevalence values reflect percentages of isolates within each indicated subgroup.

Fig 2

Principal coordinate analysis (PCoA) of virulence gene profiles among 267 Escherichia coli isolates. The PCoA was based on results for all 50 virulence genes studied. Each isolate is plotted based on its values for PCoA coordinates 1 (x axis) and 2 (y axis), which collectively capture 64.5% of total variance in the data set. For ST131, 47 H30-Rx, 15 other H30, and 9 non-H30 isolates were evaluated; for non-ST131, 51 ESBL-producing and 145 non-ESBL-producing isolates were evaluated.