Combined action of sulfadiazine and trimethoprim.

It has been claimed that trimethoprim, 2,4diamino 5 (3',4',5' trimethoxybenzyl)pyrimidine, exerts a "synergistic" effect when combined with sulfonamides (Hitchings, Drugs, Parasites and Hosts, p. 202, J. and A. Churchill, Ltd., London, 1962) and polymyxin (Garrod and Waterworth, J. Clin. Pathol. 15:328, 1962) in experimental infection of mice and natural 0.5 ml of a 5% suspension of granular hog mucin (1701-W; Wilson Laboratories, Chicago, Ill.). Appropriate controls were included (Table 1). Mice found dead the next morning were assumed to have died from gastric intubation and were excluded from the experiment. Deaths from the above dose of the Smith strain occur characteristically at 48 hr and within a day or so