抄録
In vitro the development of the resistance against SM and INH was studied by using mycobacterium avium and the following result was obtained.
1) In inoculating a large quantity (10-1mg) the bacilli resistant to SM and INH appeared in the highly concentrated medium but with a little quantity (10-4mg) no bacilli appeared.
2) When successively cultured on medium of lowly concentrated antituberculous drugs, the development of resistant bacilli was slight.
3) In intermittend inoculation to medium contained drugs, the change of resistance was almost the same in successive culture.
4) In SM-resistant bacilli, the resistance to INH was the same in the sensitive bacilli.
5) INH-resistant bacilli has less tendency to obtain SM resistance than the sensitive bacilli.
