Abstract: Objective To observe preventive effect of Mycobacterium vaccae vaccine for M.tuberculosis infected people.Methods and Result People aged from 18 to 45 whose PPD test Results are strong positive are divided into three groups at random.The average induration diameter of Mycobacterium vaccae vaccine group decreases significantly after having been injected three months,The number of those who have blister or necrosis also decrease greatly.While taking INH group and nontreatment group have no difference.Five people fell ill one year later,one from taking INH group,the other four from comparative group.No patients are found in Mycobacterium vaccae vaccine group.Conclusion Mycobacterium vaccae vaccine has better preventive effect for M.tuberculosis infected people.

Key words: Mycobacterium vaccae vaccine, prevention, M.tuberculosis infection