Enteropathogenicity markers in Escherichia coli isolated from infants with acute diarrhoea and healthy controls in Rio de Janeiro, Brazil

J Med Microbiol. 1998 Sep;47(9):781-90. doi: 10.1099/00222615-47-9-781.

Abstract

Faeces from urban children < 2 years old with acute diarrhoeal illness and from non-diarrhoeal infants (controls) were examined for Escherichia coli and other enteropathogens. A total of 990 E. coli isolates from 100 patients and 50 controls was tested for enteropathogenic E. coli (EPEC) serotype (O:H), adherence to HEp-2 cells after incubation for 3 and 6 h, fluorescent actin staining (FAS), DNA hybridisation with EAF, eaeA, STh, STp and EAggEC probes and production of heat-labile enterotoxin (LT) and verocytotoxin (VT) with Y1 and Vero cells. EPEC were the most prevalent enteropathogens in patients (32.7%; and 14% in controls). Enteroinvasive E. coli (EIEC) and Vero cytotoxin-producing E. coli (VTEC) were not detected. The rate of isolation of enterotoxigenic E. coli (ETEC) was identical in both groups. Among the EPEC isolates the prevalent serotypes were O111:H2, O55:NM and O119:H6. Localised adherence (LA) was found significantly more frequently in isolates from patients (19.6%) than controls (2.1%). All LA-positive EPEC isolates were FAS+ and eaeA+, but only 75.2% of them hybridised with the EAF probe. Diffusely adhering E. coli (DAEC) and enteroaggregative E. coli (EAggEC) were found with equal frequency in patients and controls. Twenty-seven E. coli isolates were negative for EAF but positive for eaeA and FAS and produced LA in 6-h adherence tests. These EAF-/eaeA+ strains were the only putative enteropathogen identified in seven patients and were not found in controls. The ability of these strains to elicit ultrastructural cell alterations and cell-signalling events was evaluated in Caco-2 cells (human colon carcinoma cell line) by the gentamicin invasion assay and by transmission electron microscopy. The numbers of intracellular bacteria in cell invasion tests varied from 0.4% to 1.6% of the cell-associated bacteria after a 6-h incubation period. Tyrosine phosphorylation of host cell proteins was assessed in HEp-2 cells by immunofluorescence microscopy and all strains gave positive results. EAF-/eaeA+ E. coli strains express most of the virulence properties found among true EPEC strains and can be a relevant cause of infant diarrhoea in developing countries.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Agglutination Tests
  • Bacterial Adhesion
  • Bacterial Toxins / biosynthesis
  • Brazil / epidemiology
  • Caco-2 Cells
  • Cell Line
  • Cytotoxins / biosynthesis
  • DNA Probes
  • Diarrhea, Infantile / epidemiology
  • Diarrhea, Infantile / microbiology*
  • Enterotoxins / biosynthesis
  • Escherichia coli / classification
  • Escherichia coli / isolation & purification
  • Escherichia coli / pathogenicity*
  • Escherichia coli Infections / epidemiology
  • Escherichia coli Infections / microbiology*
  • Escherichia coli Proteins*
  • Feces / microbiology
  • Humans
  • Incidence
  • Infant
  • Nucleic Acid Hybridization
  • Prevalence
  • Serotyping
  • Shiga Toxin 1
  • Urban Population
  • Virulence

Substances

  • Bacterial Toxins
  • Cytotoxins
  • DNA Probes
  • Enterotoxins
  • Escherichia coli Proteins
  • Shiga Toxin 1
  • heat-labile enterotoxin, E coli