Trimethoprim: laboratory and clinical studies.

Trimethoprim is a synthetic compound which arrests the step in bacterial purine synthesis immediately succeeding that interfered with by sulphonamides. Acting alone it inhibits the growth of a wide range of bacteria in generally much lower concentrations than sulphonamides. Its action with a sulphonamide is strongly synergic and bactericidal.Studies are described of suitable cultural conditions, methods of testing sensitivity, and acquired resistance. Some clinical results of its use are reported in respiratory tract infections, Gram-negative septicaemia, and urinary tract infections, and further therapeutic possibilities are discussed.