Mycobacterium tuberculosis のMinocycline 耐性形式
1981 年 56 巻 10 号 p. 459-463
詳細
1981 年 56 巻 10 号 p. 459-463
It has been shown recently that minocycline exhibits growth-inhibitory effect on Mycobacterium tuberculosis. In the present study, we studied the pattern of resistance development to this agent. A series of studies on this subject were done in this laboratory for various antituberculous agents. Ogawa egg medium was used. The level of resistance was estimated by the “actual count method”. It was expressed as the highest concentration of agent, on which 10 to 100 viable bacteria inoculated per medium can grow as countable colonies after incubation at 37°Cfor 4 weeks.
The number of phenotypes of resistant mutants (number of the kinds of survival curves shown by strains each derived from single colony) was two in minocycline resistance. The upper limit of resistance (the highest concentration of agent on which test organisms that were obtained by repeated selections of resistant mutants can grow) was 50μg/ml, i. e., 50 fold of the level of resistance of the parent strain. Resistant mutants that show the highest level of resistance could be obtained by obligatory two-step pattern.
