依赖利福平结核分支杆菌在无利福平条件下的生长情况研究

目的 探讨依赖利福平结核分支杆菌（依R菌）在无R条件下的生长情况。方法 取初步研究的典型依R菌株，挑取最佳R浓度管中的单个菌落，制备10^-4mg/ml菌液，分别接种于L－J和12B液体培养基，37℃培养；对比观察不同试验管细菌的生长速度、特点以及光镜、电镜下的菌体形态。结果 L－J培养有R管2周可见菌落，无R管3周才见到细小菌落；12B液体培养，前者9天获得阳性指数，后者需13天。有R管中菌落生长粗大、凸起、花菜样、易刮取和乳化；无R管中菌落生长细小、扁平、荷包蛋样、不易刮取和乳化。光镜下有R管菌体粗大、深染；无R管菌体细小、浅染，且大小不等。透射电镜下有R管菌体细胞壁完整，无R管菌体细胞壁缺陷。结论 依R菌在无R条件下可呈细胞L型样改变。

Growth of rifampin-dependent Mycobacterium tuberculosis in conditions without rifampin

OBJECTIVE: To study the growth of rifampin-dependent Mycobacterium tuberculosis in conditions without rifampin. METHODS: A typical rifampin-dependent strain was identified and a single colony growing in the optimal concentration of rifampin was selected and inoculated (10(-4) mg/ml) to L-J and 12B liquid media, cultured at 37 degrees C. The bacterial growth and characteristics were studied. RESULTS: In the L-J medium containing rifampin, bacterial growth was observed in two weeks, but in the medium without rifampin tiny colonies were not observed until three weeks. In the 12B media with and without rifampin, bacterial growth was evident on day 9 and day 13 respectively. Thick and larger colonies and cauliflower-like growth were observed in media containing rifampin, but smaller colonies and fried egg-like growth were observed in media without rifampin. Microscopic study showed thick and heavily stained bacteria in media containing rifampin, but small and lightly stained bacteria in media without rifampin. Transmission electron microscopy demonstrated that bacteria growing in the presence of rifampin had complete cell walls, but those growing in the absence of rifampin had abnormal cell walls. CONCLUSION: Rifampin-dependent Mycobacterium tuberculosis may be changed into bacterial L-forms in media without rifampin.