THE EFFECT OF PARA-AMINOBENZOIC ACID ON THE CHEMO- THERAPEUTIC ACTIVITY OF THE SULFONAMIDES IN LYMPHO- GRANULOMA VENEREUM AND IN DUCK MALARIA

It is now well established that para-aminobenzoic acid inhibits the action of sulfonamides on bacteria in vitro and in vivo.(Rubbo and Gillespie, 1940; Selbie, 1940; Woods, 1940). Wiedling (1941) found that para-aminobenzoic acid pro-duced an inhibition of the effect of sulfanilamide, sulfapyridine and sulfathiazole on the fresh water diatom Nitzschia palea var. debilis. Experiments published by Dimond (1941) showed that para-aminobenzoic acid interfered with the action of sulfanilamide on the fungus Trichophyton purpureum. Findlay (1940) has reported that para-aminobenzoic acid inhibited the action of sulfanilamide on a strain of lymphogranuloma venereum. In this communication experiments will be reported which demonstrate the inhibiting effect of para-aminobenzoic acid on the chemotherapeutic activity of sulfamethyldiazine in Plasmnodium lophurae infections in Pekin ducklings. Ex-periments will also be presented in which, contrary to the experience of Findlay (1940), we were unable to show that para-aminobenzoic acid neutralized the action of sulfanilamide and sulfamethyldiazine on a strain of lymphogranulom