title: Detection of enteroaggregative Escherichia coli in faecal samples from patients in the community with diarrhoea.
abstract: The aim of this study was to assess the usefulness of a multiplex PCR assay targeting the aat, aaiA and astA genes for the detection of typical and atypical enteroaggregative Escherichia coli (EAEC) in bacterial cultures from faecal samples from patients with community-acquired diarrhoea. The isolates harbouring these genes were also tested using the HEp-2 cell-adhesion assay to clarify their EAEC status. aat, aai or astA was found in E. coli faecal isolates from 39 (7.8 %) of 500 patients, and 20 of these strains adhered to HEp-2 cells in a pattern characteristic of EAEC. Eight isolates carrying the aai or astA gene but not the aat gene were shown to be HEp-2 cell test positive, although 12 strains with this genotype were HEp-2 cell test negative. Using the HEp-2 adhesion assay as the gold standard, the addition of primers detecting aaiA and astA to the aat PCR increased the number of EAEC isolates detected, but identified strains of E. coli that were not EAEC. The variety of genotypes exhibiting aggregative adherence highlights the problems associated with developing a molecular diagnostic test for EAEC. This PCR assay detects a variety of strains exhibiting characteristics of the EAEC group, making it a useful tool for identifying both typical and atypical EAEC.
authors.affiliation: Laboratory of Enteric Pathogens, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Claire
authors.initials: C
authors.lastname: Jenkins
authors.affiliation: University Department of Paediatric Gastroenterology, Royal Free Hospital, Pond Street, London NW3 QG, UK.|Tropical Diseases Research Centre, Microbiology Unit, PO Box 71769, Ndola, Zambia.
authors.forename: Mathias
authors.initials: M
authors.lastname: Tembo
authors.affiliation: Laboratory of Enteric Pathogens, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Henrik
authors.initials: H
authors.lastname: Chart
authors.affiliation: Laboratory of Enteric Pathogens, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Tom
authors.initials: T
authors.lastname: Cheasty
authors.affiliation: Laboratory of Enteric Pathogens, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Geraldine A
authors.initials: GA
authors.lastname: Willshaw
authors.affiliation: University Department of Paediatric Gastroenterology, Royal Free Hospital, Pond Street, London NW3 QG, UK.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Phillips
authors.affiliation: Yorkshire and Humber, Leeds Health Protection Agency Laboratory, Bridle Path, York Road, Leeds LS15 7TR, UK.
authors.forename: David
authors.initials: D
authors.lastname: Tompkins
authors.affiliation: Laboratory of Enteric Pathogens, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK.
authors.forename: Henry
authors.initials: H
authors.lastname: Smith
mesh_terms: D018830:Adhesins, Escherichia coli / Q000737:chemistry / Q000235:genetics; D000293:Adolescent; D000328:Adult; D001422:Bacterial Adhesion / Q000502:physiology; D002460:Cell Line; D002648:Child; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D003967:Diarrhea / Q000175:diagnosis / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics / Q000302:isolation & purification*; D004927:Escherichia coli Infections / Q000175:diagnosis / Q000382:microbiology*; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction / Q000379:methods*; D012703:Serotyping; D014195:Travel
chemical_list: D018830:Adhesins, Escherichia coli; D004269:DNA, Bacterial