Abstract
The faecal flora of 21 patients with proctocolitis and five patients with Crohn's disease of the large bowel was examined both while sulphasalazine was being administered and during control periods. Patients with proctocolitis and Crohn's disease who were not receiving sulphasalazine had a similar flora which did not differ in any way from the normal. The effect of sulphasalazine was to decrease the numbers of opalescent-negative clostridia, enterobacteria, and total non-sporing anaerobes. It is suggested that this antibacterial effect of sulphasalazine, which has not been previously demonstrated, may be related to the beneficial effects of this drug in proctocolitis and should be investigated further.