Effects of Trimethoprim and Sulfisoxazole, Alone and in Combination, on Growth and Carriage of Neisseria meningitidis

Sulfisoxazole or sulfadiazine in combination with trimethoprim (TMP) inhibited the growth of strains of meningococci markedly resistant to the sulfonamides. In two trials of administration of these drugs to volunteers among military recruits who were carriers of Neisseria meningitidis, this marked effectiveness in vitro was not duplicated. It was not ascertained whether these in vivo failures resulted from inadequate absorption of TMP, insufficient excretion into saliva or nasal mucus, or both.