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J Clin Microbiol. 2016 Aug;54(8):2128-34. doi: 10.1128/JCM.00711-16. Epub 2016 Jun 1.

Phylogenetic Analysis of Enteroaggregative Escherichia coli (EAEC) Isolates from Japan Reveals Emergence of CTX-M-14-Producing EAEC O25:H4 Clones Related to Sequence Type 131.

Author information

1
Department of Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
2
Osaka Prefectural Institute of Public Health, Osaka, Japan.
3
Clinical Laboratory, Kagoshima University Hospital, Kagoshima, Japan.
4
Department of Animal and Grassland Sciences, Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan.
5
Department of Infection Control and Prevention, Division of Medical and Environmental Safety, Kagoshima University Hospital, Kagoshima, Japan.
6
Department of Microbiology, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.
7
Department of Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan Department of Infection Control and Prevention, Division of Medical and Environmental Safety, Kagoshima University Hospital, Kagoshima, Japan nishi1@m2.kufm.kagoshima-u.ac.jp.

Abstract

Enteroaggregative Escherichia coli (EAEC) causes acute or persistent diarrhea. The aggR gene is widely used as a marker for typical EAEC. The heterogeneity of EAEC is well known; however, there are few reports on the phylogenetic relationships of EAEC. Recently, CTX-M extended-spectrum β-lactamase (ESBL)-producing EAEC strains have been reported worldwide. To characterize EAEC strains in Japan, we investigated the population structure of EAEC. A total of 167 aggR-positive strains isolated from stool specimens from diarrheal patients in Kagoshima (139 strains) and Osaka (28 strains), Japan, between 1992 and 2010 were examined for the prevalence of EAEC virulence markers, the blaCTX-M gene, and the capacity to form biofilms. Multilocus sequence typing was also conducted. EAEC strains were widely distributed across four major E. coli phylogroups. Strains of O111:H21/clonal group 40 (CG40) (30 strains), O126:H27/CG200 (13 strains), and O86a:H27/CG3570 (11 strains) in phylogroup B1 are the historical EAEC clones in Japan, and they exhibited strong biofilm formation. Twenty-nine strains of EAEC O25:H4/CG131 were identified in phylogroup B2, 79% of which produced CTX-M-14. This clone has emerged since 2003. The clone harbored plasmid-encoded EAEC virulence genes but not chromosomal virulence genes and had lower biofilm-forming capacity than historical EAEC strains. This clone most likely emerged from a pandemic uropathogenic O25:H4/sequence type 131 clone by acquiring an EAEC virulence plasmid from canonical EAEC. Surveillance of the horizontal transfer of both virulence and ESBL genes among E. coli strains is important for preventing a worldwide increase in antimicrobial drug resistance.

PMID:
27252465
PMCID:
PMC4963495
DOI:
10.1128/JCM.00711-16
[Indexed for MEDLINE]
Free PMC Article

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