The faecal flora in ulcerative colitis.

Differential counts of the faecal flora of patients with ulcerative colitis showed a dysbiotic flora with a 100-fold increase of group-D streptococci and a reduction of bifidobacteria in comparison with the stable eubiotic flora of healthy subjects. The increase in number in group-D streptococci was accompanied by an increase in variety. About four different varieties of enterococci were found in faeces from patients compared with one or two in samples from healthy subjects. The strains isolated from patients were more active in mucin breakdown, and only strains from patients were able to break down hyaluronic acid. Lactic acid could be formed from these substrates. The increased secretion of mucin in colitis and the presence of unprotected hyaluronic acid in ulcers seem to select these organisms which are probably the cause of the high lactic-acid content of the faeces in such patients.