Background: Reduced sulphur compounds, such as sulphide, have been implicated in ulcerative colitis (UC).1 Sulphide may be produced either from fermentation of sulphur amino acids or reduction of sulphate by sulphate reducing bacteria (SRB). In faecal slurries ASA and sulphasalazine (SAS) have been shown to reduce sulphide production from sulphate2 and from methionine.3

Aims: To look at the effects of SAS, ASA and sulphapyridine (SP) in pure cultures on sulphide production from SO₄ by SRB and sulphur amino acids by an amino acid fermenter.

Methods: An amino acid fermenter producing sulphide was isolated from a human faecal sample and provisionally identified as a fusobacterium. Desulphovibrio desulphuricans was the SRB used. The SRB was grown in Postgate C in universals and the fusobacterium was grown in Wilkins Chalgren anaerobe broth with 0.5g/l cysteine and 0.5g/l methionine. Concentrations of SAS, ASA or SP from 0 to 40mM were added to the universals prior to autoclaving. 20mM ASA is considered physiological. After cooling 0.5ml fusobacterium or SRB stock was injected into each universal and the culture was incubated at 37⁰C for 18hr. 1ml of solution was used for sulphide determination by microdistillation and HPLC.

Results: SAS achieved a 90% inhibition of sulphide production from SRB and fusobacterium at 1mM and 5mM respectively. ASA 90% inhibited SRB at 20mM but only achieved about 50% inhibition from fusobacterium over the target range. SP had no significant effect on sulphide production from either bacterium.

Conclusion: In pure bacterial cultures SAS is more effective than ASA at inhibiting sulphide production from SO₄ and sulphur amino acids.