Global Escherichia coli Sequence Type 131 Clade with bla(CTX-M-27) Gene

The Escherichia coli sequence type (ST) 131 C2/H30Rx clade with the bla(CTX-M-15) gene had been most responsible for the global dissemination of extended-spectrum β-lactamase (ESBL)–producing E. coli. ST131 C1/H30R with bla(CTX-M-27) emerged among ESBL-producing E. coli in Japan during the late 2000s. To investigate the possible expansion of a single clade(,) we performed whole-genome sequencing for 43 Japan and 10 global ST131 isolates with bla(CTX-M-27) (n = 16), bla(CTX-M-14) (n = 16), bla(CTX-M-15) (n = 13), and others (n = 8). We also included 8 ST131 genomes available in public databases. Core genome-based analysis of 61 isolates showed that ST131 with bla(CTX-M-27) from 5 countries formed a distinct cluster within the C1/H30R clade, named C1-M27 clade. Accessory genome analysis identified a unique prophage-like region, supporting C1-M27 as a distinct clade. Our findings indicate that the increase of ESBL-producing E. coli in Japan is due mainly to emergence of the C1-M27 clade.