Synergistic fungistatic effect of tetrazolium-saliva mixtures.

Abstract

THE presence of an antifungal factor has been reported in normal human serum and in the conjunctival mucosa1–3. This work was initiated to determine whether saliva possesses an identical or similar substance. Stimulated whole saliva, parotid and sub-maxillary secretions were collected from ten apparently normal individuals and tested by placing aliquots in cylinders on Pagano–Levin agar, lawn seeded with Candida albicans, Candida tropicalis and Saccharomyces cerevisiae. No zones of inhibition were observed. Serum constituents (globulins) excreted in saliva are approximately one tenth of their concentration in serum and so it was decided to concentrate the salivary specimens to dryness by lyophilization. The solid constituents were then resuspended in sterile distilled water to give final concentrations 2.5–20 times greater than in saliva. Such concentrations manifested anti-fungal properties when tested as previously described. No inhibitory activity was discernible when Sabouraud's glucose agar, blood brain heart infusion agar or brain heart infusion agar were used, and so it seemed that the constituent in the Pagano–Levin medium which might be responsible for this activity was triphenyltetrazolium chloride, a redox indicator. The compound is reduced by Candida tropicalis to a red pigmented crystalline formazan whereas strains of Candida albicans usually fail to do so. At least five times the concentration of tetrazolium salt in Pagano–Levin medium is necessary for inhibition.