Increased extended-spectrum β-lactamase–producing E. coli in Japan resulted mainly from a clade containing this gene.

This Japanese regional ESBL-producing E. coli epidemic is closely associated with newly identified CTX-M-27- and CTX-M-14-producing ST131 H30R subclonal groups and with mobile elements IS26, ISEcp1 and IS903D.

Escherichia coli sequence type 131 (ST131) is a pandemic clonal lineage that is responsible for the global increase in fluoroquinolone resistance and extendedspectrum-␤-lactamase (ESBL) producers. The members of ST131 clade C, especially subclades C2 and C1-M27, are associated with ESBLs. We developed a multiplex conventional PCR assay with the ability to detect all ST131 clades (A, B, and C), as well as C subclades (C1-M27, C1-nM27 [C1-non-M27], and C2). To validate the assay, we used 80 ST131 global isolates that had been fully sequenced. We then used the assay to define the prevalence of each clade in two Japanese collections consisting of 460 ESBL-producing E. coli ST131 (2001-12) and 329 E. coli isolates from extraintestinal sites (ExPEC) (2014). The assay correctly identified the different clades in all 80 global isolates: clades A (n ϭ 12), B (n ϭ 12), and C, including subclades C1-M27 (n ϭ 16), C1-nM27 (n ϭ 20), C2 (n ϭ 17), and other C (n ϭ 3). The assay also detected all 565 ST131 isolates in both collections without any false positives. Isolates from clades A (n ϭ 54), B (n ϭ 23), and C (n ϭ 483) corresponded to the O serotypes and the fimH types of O16-H41, O25b-H22, and O25b-H30, respectively. Of the 483 clade C isolates, C1-M27 was the most common subclade (36%), followed by C1-nM27 (32%) and C2 (15%). The C1-M27 subclade with bla CTX-M-27 became especially prominent after 2009. Our novel multiplex PCR assay revealed the predominance of the C1-M27 subclade in recent Japanese ESBL-producing E. coli isolates and is a promising tool for epidemiological studies of ST131.

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. Adult patients treated for E. coli bacteremia in four hospitals were retrospectively evaluated. The 30-day mortality rates in patients belonging to the ESBL-CF, ESBL-carbapenem, and non-ESBL-CF groups were compared as 2 (empirical and definitive therapy) cohorts. The adjusted hazard ratios (aHRs) for mortality were calculated using Cox regression models with weighting according to the inverse probability of propensity scores for receiving CF or carbapenem treatment.

Contamination of surface waters by antimicrobial-resistant bacteria and pathogenic bacteria is a great concern. In this study, 531 Escherichia coli isolates obtained from the Yamato River in Japan were evaluated phenotypically for resistance to 25 antimicrobials. Seventy-six isolates (14.3%) were multidrug resistant (MDR), 66 (12.4%) were nonsusceptible to one or two classes of agents, and 389 (73.3%) were susceptible. We performed whole-genome sequencing of selected strains by using Illumina technology. In total, the genome sequences of 155 strains were analyzed for antibiotic resistance determinants and phylogenetic characteristics. More than 50 different resistance determinants, including acquired resistance genes and chromosomal resistance mutations, were detected. Among the sequenced MDR strains (n ϭ 66), sequence type 155 (ST155) complex (n ϭ 9), ST10 complex (n ϭ 9), and ST69 complex (n ϭ 7) were prevalent. Among extraintestinal pathogenic E. coli (ExPEC) strains (n ϭ 58), clinically important clonal groups, namely, ST95 complex (n ϭ 18), ST127 complex (n ϭ 8), ST12 complex (n ϭ 6), ST14 complex (n ϭ 6), and ST131 complex (n ϭ 6), were prevalent, demonstrating the clonal distribution of environmental ExPEC strains. Typing of the fimH (type 1 fimbrial adhesin) gene revealed that ST131 complex strains carried fimH22 or fimH41, and no strains belonging to the fimH30 subgroup were detected. Fine-scale phylogenetic analysis and virulence gene content analysis of strains belonging to the ST95 complex (one of the major clonal ExPEC groups causing community-onset infections) revealed no significant differences between environmental and clinical strains. The results indicate contamination of surface waters by E. coli strains belonging to clinically important clonal groups.IMPORTANCE The prevalence of antimicrobial-resistant and pathogenic E. coli strains in surface waters is a concern because surface waters are used as sources for drinking water, irrigation, and recreational purposes. In this study, MDR and ExPEC strains in river water were characterized by genomic sequencing and analysis. We detected more than 50 resistance determinants and identified clonal groups specific to MDR and ExPEC strains. This study showed contamination of surface waters by E. coli strains belonging to clinically important clonal groups. Overall, this study advances our understanding of environmental MDR and ExPEC strains.KEYWORDS antimicrobial resistance, Escherichia coli, ExPEC, whole-genome sequencing E scherichia coli is a commensal member of the gastrointestinal tract of humans and other warm-blooded animals. Consequently, E. coli, as well as Enterococcus spp., has long been used as an indicator of fecal contamination to assess the microbial quality of surface waters. Although most E. coli strains are harmless, some strains are pathogenic

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