1. Antibacterial activities of sulfamethoxazole (SMX), trimethoprim (TMP) and SMX-TMP combination (5 : 1) were investigated against 26 strains of Hemophilus influenzae isolated from patients with chronic respiratory tract infections. The distribution of sensitivities as determined by a modified LEVINTHAL method indicated that the bacterial sensitivities were largely dependent upon their sensitivity to TMP under the tested conditions.
2. The potentiation of antibacterial activities by SMX-TMP combination mixed at a ratio of 5 : 1 was clearly confirmed in an experiment employing subcutaneous infection with Hemophilus influenzae in mice.
3. A clinical trial of SMX-TMP combination product (SMX 400 mg and TMP 80 mg per tablet) in dosages 4-6 tablets daily in 7 patients with respiratory tract infections, 7 patients with urinary tract infections and 1 patient with Salmonella carriers demonstrated that this preparation is effective as long as pathogenic organisms isolated from the clinical materials were sensitive to the combination in vitro. Aside from a single case of drug examthem, no adverse reaction has been recorded.
Further experience is required to confirm the effect of this combination product in Salmonella carriers.