Prevalence and Characteristics of Sequence Type 131 Escherichia coli Isolated from Children with Bacteremia in 2000–2015

Escherichia coli sequence type (ST) 131 has emerged as a higher virulent and multidrug-resistant pathogen worldwide. This study aimed to identify the prevalence and characteristics of E. coli ST131 isolated from Korean children with bacteremia at a single center for 16 years. We retrospectively reviewed culture-proven E. coli bacteremia cases of children aged ≤18 years between 2000 and 2015. E. coli isolates were analyzed using multilocus sequence typing, fimH typing, and CTX-M typing. Among 177 children with E. coli bacteremia, a total of 21 (11.9%) ST131 isolates and 37 (20.9%) extended spectrum β-lactamase (ESBL)-producing E. coli were identified. Nineteen (90.5%) isolates of ST131 E. coli had the fimH gene, of which three were assigned to subclone H30. There was a significant difference in prevalence of ESBL production between ST131 ( n = 8, 38.1%) and non-ST131 ( n = 29, 18.6%) isolates ( p = 0.039). Five ESBL-producing ST131 E. coli isolates had the bla CTX-M gene: two carried bla CTX-M-14 , two carried bla CTX-M-15 , and one carried both bla CTX-M-14 and bla CTX-M-15 . ST131 isolates had higher resistance rates to piperacillin/tazobactam (38.5% vs. 10.0%), cefotaxime (38.1% vs. 16.7%), amikacin (23.8% vs. 1.9%), and gentamicin (52.4% vs. 28.8%) than non-ST131 isolates ( p