Risk Factors and Molecular Features of Sequence Type (ST) 131 Extended-spectrum β-Lactamase-producing Escherichia coli in Community-onset Bacteremia

Due to the spread of a single CTX-M-type extended-spectrum β-lactamase (ESBL) clone of sequence type (ST) 131, community-onset bacteremia caused by ESBL-producing Escherichia coli has increased dramatically. We evaluated the risk factors and molecular features of ESBL-producing E. coli ST131 clones isolated from Korean patients with community-onset bacteremia. We collected a total of 124 ESBL-producing E. coli isolates from blood in patients with community-onset bacteremia over a 2 year-period. Among 124 patients, the number of community-associated bacteremia cases was 57 (46%). ST131 strains accounted for 49.1% (28/57) of community-associated bacteremia cases and 44.8% (30/67) of healthcare-associated community-onset bacteremia cases. Among 58 ST131 strains, nine isolates were shown to harbor O16-H41, and 61.1% (30/49) of O25 had H30Rx. In a multivariate analysis, independent risk factors for acquisition of ST131 isolates over non-ST131 isolates were underlying diabetes mellitus and absence of prior chemotherapy history. The most common ESBL genotype was CTX-M-15 (46.0%), followed by CTX-M-14 (37.1%). A considerable proportion of community-onset ESBL-producing E. coli bacteremia was observed. ST131 clones appear to be associated with the spread of community-associated bacteremia exhibiting high antimicrobial resistance and highly virulent H30Rx traits, which could become a major public health concern in Korea.