Expression of Bacteroides fragilis virulence markers in vitro.
Bacteroides fragilis isolates from intestinal and non-intestinal infections, normal flora and the environment were examined for properties linked with interactions among cells in vitro. Different adhesion molecules were detected in agglutination assays with human erythrocytes and tests for auto-agglutination and adherence to human colon carcinoma cells (HT29). There was no correlation between these properties, indicating that independent molecules are involved. Treatment with trypsin, heat or EDTA inhibited agglutination and adherence, suggesting that these molecules are proteins. The lack of correlation with the origin of the strains did not permit any of these activities to be recognised as virulence markers. The expression of fragilysin, a protease associated with damage to intestinal cells and bacterial translocation, was examined. Only those strains from patients with diarrhoea expressed this protease activity in assays with HT29 cells and this was confirmed by specific PCR for the bft gene. The activity of fragilysin as an enterotoxin was confirmed in the rabbit intestinal ligated loop assay. The association of this property only with strains from intestinal infections indicates that it is too early to suggest this protease as a determinant factor of B. fragilis invasiveness.
Ferreira
R
R
Instituto de Microbiologia, UFRJ, Rio de Janeiro, RJ, Brazil.
Alexandre
M C F
MCF
Instituto de Microbiologia, UFRJ, Rio de Janeiro, RJ, Brazil.
Antunes
E N F
ENF
Instituto de Microbiologia, UFRJ, Rio de Janeiro, RJ, Brazil.
Pinhao
A T
AT
FIOCRUZ, Rio de Janeiro, RJ, Brazil.
Moraes
S R
SR
Instituto de Microbiologia, UFRJ, Rio de Janeiro, RJ, Brazil.
Ferreira
M C S
MCS
Instituto de Microbiologia, UFRJ, Rio de Janeiro, RJ, Brazil.
Domingues
R M C P
RMCP
Instituto de Microbiologia, UFRJ, Rio de Janeiro, RJ, Brazil.
D000372:Agglutination Tests; D000818:Animals; D000925:Anticoagulants / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D001442:Bacteroides Infections / Q000382:microbiology*; D001441:Bacteroides fragilis / Q000187:drug effects / Q000235:genetics / Q000472:pathogenicity*; D004492:Edetic Acid / Q000494:pharmacology; D004768:Enterotoxins / Q000235:genetics; D019073:HT29 Cells; D006386:Hemagglutination Tests; D006358:Hot Temperature; D006801:Humans; D007082:Ileum / Q000382:microbiology; D007410:Intestinal Diseases / Q000382:microbiology; D008666:Metalloendopeptidases / Q000235:genetics; D016133:Polymerase Chain Reaction; D011817:Rabbits; D013499:Surface Properties; D014357:Trypsin / Q000494:pharmacology; D014774:Virulence; D014871:Water Microbiology; D014876:Water Pollution
D000925:Anticoagulants; D004768:Enterotoxins; D004492:Edetic Acid; D014357:Trypsin; D008666:Metalloendopeptidases; C091198:fragilysin