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

Abstract

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 < 0.05, for all). There were no significant differences in the rate of shock and mortality between patients infected with ST131 (16.7% and 5.6%) and non-ST131 isolates (24.2% and 9.8%). Prevalence of ST131 E. coli causing bacteremia in children was not different from that in adults or that causing urinary tract infection in children in Korea. However, because ST131 clones are more likely to be ESBL producing and more resistant to empirical antibiotics used in sepsis than are non-ST131 clones, surveillance for the prevalence of ST131 and its drug resistance should be continued.