Abstract
Vitamin B_<12> concentration in the blood of patients with pulmonary tuberculosis treated with PAS and streptomycin was higher than that of patients treated with PAS and INAH. The reason seems to be attributed to the difference of the range of antibiotic spectrum between streptomycin and INAH. In the daily oral administration of 250 mg of streptomycin, vitamin B_<12> concentration in the blood markedly increased in 3 to 5 days and decreased thereafter. But the retention of high blood level of the vitamin was observed in the reduced dose of streptomycin to 20-50 mg even after 2 weeks. Almost the same result was obtained in the oral administration of bicillin. These results might be interpreted by the change and the aquirement of resistance of intestinal bacterial flora.
