[Changes in the number and virulence of tubercle bacilli isolated form pulmonary tuberculosis during short course chemotherapy].

The virulence of these tubercle bacilli was compared with the mice. The sputum specimens were collected on the 0, 3, 7, 14th day and then at 2 weeks intervals up to 12th week form 20 patients on chemotherapy. 25 mice were infected intravenously with each strain. We took the mean survival time of these mice as index of virulence. The results were shown that the numbers of bacilli were rapidly reduced with a stable logarithm within 4-6 weeks after chemotherapy. But the virulence of tubercle bacilli secreted from the same patients was stable and had no significant difference statistically (P greater than 0.05) from pretreatment to 12 weeks after chemotherapy.