THE COMBINED ACTION OF PENICILLIN AND THE SULFONAMIDES IN VITRO: THE NATURE OF THE REACTION'

The combined action of penicillin and the sulfonamides against bacteria has been demonstrated by several workers. Ungar (1943) reported that penicillin and sulfapyridine showed a marked additive effect both in vitro and in vivo against Staphylococcus aureus and hemolytic streptococci. Soo-Hoo and Schnitzer (1944) reported the additive effect of penicillin when combined with sulfanilamide or sulfapyridine against streptococci. Kirby (1944) using sulfadiazine and Bigger (1944) using sulfathiazole found that these compounds when combined with penicillin showed an additive effect against staphylococci and streptococci. T'ung (1944) found the in vitro sulfathiazole-penicillin combination more effi-cient than either compound alone when tested against several strains of Brucella. Hobby and Dawson (1944a) found a slight additive effect with sulfapyridine and none with sulfadiazine when these agents were combined with penicillin and tested against staphylococci and streptococci. They also reported that the rate of penicillin activity was reduced when small amounts of the sulfonamides were added