Bernard Rowe

MULTIRESISTANT SALMONELLA TYPHIMURIUM DT104 IN CATS : A PUBLIC HEALTH RISK

1Of particular importance in this increase has been the epidemic spread of a multiresistant strain of R type ACSSuT (A ampicillin; C, chloramphenicol; S, streptomycin, Su, sulphonamides; T, tetracyclines). 1 In 1995 over 87% of strains from human beings were resistant to these five antibiotics, with 26·9% and 6·2% of strains having additional resistances to trimethoprim and ciprofloxacin, respectively. 2

HEp-2 Adhesion and the Expression of a 94 kDa Outer-membrane Protein by Strains of Escherichia coli Belonging to Enteropathogenic Serogroups

Sixty strains of Escherichia coli belonging to enteropathogenic serogroups (EPEC) were examined for the ability to adhere to HEp-2 cells, the possession of the genes encoding EPEC adherence factor (EAF) and the ability to express an outer-membrane protein (OMP) of 94 kDa thought to be involved in bacterial adhesion to eukaryotic cells. An absolute correlation was found between HEp-2 adhesion and the possession of the genes encoding EAF. An OMP of 94 kDa was observed in the SDS-PAGE profile of most adhesive strains. In some strains this protein was prone to proteolytic degradation. An antiserum raised to a HEp-2 adhesive strain of EPEC did not react with the 94 kDa OMP of all EPEC which were EAF-positive and HEp-2 adhesive, indicating some interstrain antigenic variation of this protein. Although this 94 kDa protein was surface-exposed, specific antibodies binding to the 94 kDa protein in situ in the outer membrane did not interfere with adhesion of EPEC to HEp-2 cells. Therefore, these studies question the value of this protein as a potential vaccine component.

USE OF ANTISERA FOR IDENTIFICATION OF ENTEROTOXIGENIC ESCHERICHIA COLI

The usual methods for identifying enterotoxigenic Escherichia coli (ETEC) strains involve testing for production of heat-labile enterotoxins. To simplify the identification of ETEC, antisera against common ETEC O serogropus were used to identify ETEC in the stools from 618 patients with acute diarrhoea and dehydration (greater than or equal to 5% loss of body-weight) receiving treatment at a hospital in Dacca, Bangladesh. Compared with enterotoxin testing the antisera had a sensitivity of 64%, a specificity of 96%, and a predictive accuracy of 89%. These antisera may be useful in the identification ETEC in clinical laboratories which are unable to perform toxin testing and should be evaluated in other geographical areas.

Identification of enteric pathogens in the small and large intestine of children with diarrhea

Enteric pathogens were identified in children with diarrhea from duodenal specimens obtained with a string capsule and from fecal specimens. Rotavirus was identified in stools of 43 of 100 children, and was recovered from the small intestine from nine (21%) children who were excreting this virus. Shigella was isolated from stools from 22, Salmonella from 17, enterotoxigenic Escherichia coli from eight, and Aeromonas hydrophila from one of 100 children with diarrhea. In contrast to rotavirus, Salmonella, Shigella, enterotoxigenic Escherichia coli, and A. hydrophila were not isolated from the small intestine. Nonenterotoxigenic Aeromonas species were recovered from the small intestine, but not the stool of five children. These children were also infected with Shigella or with rotavirus; this suggests that Aeromonas was not the cause of their diarrhea. None of 51 Escherichia coli isolated with the string capsules, or 67 isolated from stool that agglutinated in commercial enteropathogenic Escherichia coli antisera were of classical enteropathogenic Escherichia coli serotypes. One hundred and five of these 118 Escherichia coli did not hybridize with a deoxyribonucleic acid probe for plasmid mediated factors conferring adherence to HeLa cells. Examination of specimens collected with a string capsule from children with diarrhea did not identify any more enteric pathogens than examining stools. Furthermore testing Escherichia coli for agglutination in commercial enteropathogenic Escherichia coli antisera did not identify Escherichia coli of enteropathogenic serotypes.