Abstract Background Ceftriaxone-resistant Escherichia coli infections are increasingly common, partially due to the emergence of E. coli sequence type 131 (ST131) including its subclade C2/H30Rx that produce extended-spectrum β-lactamases (ESBL). Methods A prospective cohort including 14 US sites, which enrolled monomicrobial ceftriaxone-resistant and susceptible E. coli BSI cases in a 1:1 ratio, was used to compare ST131 versus non-ST131 E. coli BSI, with specific attention to E. coli ST131 C2/H30Rx. Desirability of outcome ranking (DOOR) was determined at 30 days after infection onset. Results This analysis included 282 patients with E. coli BSI; 43% (121/282) were E. coli ST131, and 23% (66/282) belonged to the C2/H30Rx subclade. Resistance to ceftriaxone was present in 79% (96/121) ST131, 86% (57/66) E. coli ST131 C2/H30Rx, and 27% (43/161) E. coli non-ST131. Compared to patients with non-ST131 E. coli BSI, patients with ST131 BSI were older (median 70 years, Q1 62, Q3 76 years vs. 65 years, 51, 74; p = 0.005) and more often admitted from long-term care facilities (21/121 17% vs 7/161 4%, p 0.001). Overall and empiric carbapenem use was more frequent in the treatment of patients with ST131 BSI compared with non-ST131 BSI (overall 89/121 74% vs 50/161 31%; empiric: 58/121 48% vs. 31/161 19%, p 0.001). DOOR outcomes were similar between groups. Conclusions Most ceftriaxone-resistant E. coli from US patients with E. coli BSI belong to ST131, particularly E. coli ST131 C2/H30Rx, serving as an important driver of carbapenem use.
Mackow et al. (Wed,) studied this question.