抗结核药物诱导结核分支杆菌形成L型及其特性的观察

目的 观察常用抗结核药物对结核分支杆菌L型的诱导作用以及结核分支菌L型在非高渗透压培养基内的某些特性及其抗菌药物敏感性，探讨结核分支菌L型形成的机制及其在结核病的发生、诊断及治疗上的意义。方法 将结核分支杆菌接种于含有利福平、异烟肼、乙胺丁醇的非高渗透压培养基内，逐日在显微镜下观察结构分支杆菌L型的形成情况。L型形成后将培养物过滤，获得结核分支杆菌L型纯培养物并对其形态、培养、抗菌药物敏感性、结核分支杆菌特异性基因等进行观察。结果 结核分支杆菌在常规药敏试验浓度的利福平、异烟肼、乙胺丁醇的作用下均可形成L型。结核分支杆菌L型对这些抗结核药物不再敏感，但对链霉素、红霉素、氧氟沙星、诺氟沙星等抗菌药物均敏感。结核分支杆菌L型在非高渗透压培养基内呈圆球或不规则形态的细胞，单个、成双或链状排列，沉于培养基底部生长，不粘附瓶壁，不运动，抗酸染色阴性，革兰染色阴性或阳性，保留了结核分支杆菌特异性PCR引物基因序列。结论 利福平、异烟肼、乙胺丁醇虽然能够杀灭结核分支杆菌细菌型，但也能够诱导其形成L型而造成这些抗结核药物对结核治疗无效。非高渗培养基传代培养的结核分支杆菌L型保留了与其亲代细菌型一致的PCR引物基因序列，以致可用结核分支杆菌特异性PCR鉴定。根据结核分支杆菌L型的药物敏感性特点，建议在使用抗结核药物治疗中须注意其L型的形成和联合使用结核分支杆菌L型敏感的抗菌药物进行治疗。

Observations of properties of the L-form of M. tuberculosis induced by the antituberculosis drugs

Objectives To investigate the mechanism of generation of L form of M tuberculosis and its significance on the development,diagnosis and treatment of tuberculosis. Methods M tuberculosis was inoculated into the non high osmotic medium with rifampin, isoniazid or ethambutol and then the L form was observed by microscopy daily The cultures were filtrated to get the pure cultures of stable L form by subculture with the non high osmotic medium and characteristics of morphology, growth, susceptibilities to the antibacterial drugs and the special gene of M tuberculosis were observed when the pure subcultures of the L form were isolated. Results L form of M tuberculosis was induced by the concentrations of routine inhibition test of rifampin, isoniazid or ethambutol The L form would not be susceptible to the above mentioned antituberculosis drugs but susceptible to streptomycin, erythromycin, ofloxacin, norfloxacin and others The morphologies of L form were irregular or spherical with single, paired or chain form, and growth under the bottom of the medium but not movement or adhere to the glass The L form was negative by acid fast stain and negative or positive by Gram stain The gene of L form reacted with the PCR kit for the M tuberculosis and showed the same band. Conclusions M tuberculosis could be killed by rifampin, isoniazid or ethambutol but also could be induced to become the L form by these antituberculosis drugs, and it is one of the important factor that affecting the effect of treatment of the tuberculosis The cell wall deficient variants of M tuberculosis could be determined by the PCR of M tuberculosis It is recommended that the L forms should be noticed during the treatment with the antituberculosis drugs and combination treatment with antituberculous drugs to which the L forms were susceptible, is also very important.