title: Enteroaggregative Escherichia coli: incidence in Japan and usefulness of the clump-formation test.
abstract: The usefulness of the clump-formation test described by Albert et al. for identifying enteroaggregative Escherichia coli (EAggEC) and the incidence of EAggEC in Japan were studied. One hundred and seventy strains of E. coli agglutinated with enteropathogenic E. coli diagnostic antisera were collected from a variety of districts in Japan. All isolates were from diarrheal stools. EAggEC was identified on the basis of the presence of the aggR gene accompanied by aggregative adhesion to HEp-2 cells. After 24 strains carrying eaeA, elt, est, stx-1, stx-2, or ipaH genes were eliminated, the remaining 145 strains were examined for adhesion to Hep-2 cells, the presence of the aggRgene, and clump formation on the surface of Muller-Hinton broth. aggR was detected in 10 strains, and 9 of them displayed aggregative adhesion to HEp-2 cells. Seven strains produced marked clumps and 22 showed moderate clump formation. The sensitivity and specificity of the clump-formation test for detecting EAggEC were each about 90%, and they varied slightly depending on the stringency of evaluation for the degree of clump formation. From these results, we conclude that the incidence of EAggEC cannot be ignored as a possible cause of diarrheal disease in Japan, and we strongly recommend the clump-formation test for detecting EAggEC.
authors.affiliation: Department of Bacteriology, Faculty of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Nakagami-gun, Okinawa 903-0215, Japan. iwanaga@med.u-ryukyu.ac.jp
authors.forename: Masaaki
authors.initials: M
authors.lastname: Iwanaga
authors.forename: Tianyan
authors.initials: T
authors.lastname: Song
authors.forename: Naomi
authors.initials: N
authors.lastname: Higa
authors.forename: Shige
authors.initials: S
authors.lastname: Kakinohana
authors.forename: Claudia
authors.initials: C
authors.lastname: Toma
authors.forename: Noboru
authors.initials: N
authors.lastname: Nakasone
mesh_terms: D001422:Bacterial Adhesion; D002460:Cell Line; D003967:Diarrhea / Q000382:microbiology*; D004926:Escherichia coli / Q000302:isolation & purification*; D029968:Escherichia coli Proteins; D006801:Humans; D007564:Japan; D015534:Trans-Activators / Q000235:genetics
chemical_list: C088603:AggR protein, E coli; D029968:Escherichia coli Proteins; D015534:Trans-Activators