L-PHASE GROWTH OF MYCOBACTERIA
2. Consideration on the Survival of Tubercle Bacillus in Caseous Lesion
1979 Volume 54 Issue 4 Pages 231-235
Details
1979 Volume 54 Issue 4 Pages 231-235
Tubercle bacilli in caseous lesion seem to be non-acid-fast, Gram-negative granules which may revert into acid-fast rods, spread and produce new lesions when the caseous lesion begins to liquefy and form tuberculous cavity. The granular form is estimated morphologically to be L-form of tubercle bacilli. The survival mode of the bacilli in caseous lesion will be discussed.
1) Tuberculin sensitivity of the host having caseous lesion lasts positive nearly throughout whole life. On the other hand, tuberculin sensitivity terminates after certain period of time when the host is immunized with a homogenate of tubercle bacilli or living BCG, unless the infection with tubercle bacilli occurs thereafter. Above described facts indicate that the existence of metabolizing tubercle bacilli in caseous lesion is a necessary condition to maintain the tuberculin sensitivity by continuous stimulation with tuberculous antigens or their metabolites.
2) Massive acid-fast rods appear just beneath the surface of caseous mass when it begins to liquefy as the initial stage of cavity formation during the course of pulmonary tuberculosis. This indicates the reappearance of acid-fast rods from tubercle bacilli of non-acid -fast, nonrod form, which were multiplied actively and were distributed rather evenly in caseous mass.
3) Though most of anti-tuberculous drugs show antibacterial activity when they were applied to multiplying tubercle bacilli, they seem to be inactive against non-multiplying phase except rifampicin. Short course chemotherapy has become possible when rifampicin was applied in combination with isoniazid which has strong activity against the multiplying classical form of tubercle bacilli.
Above described evidences suggest that the tubercle bacilli in caseous mass are multiplying cell-wall-deficient-form, namely the L-form of tubercle bacilli. It is mandatory to study the survival status of tubercle bacilli in caseous lesion, probably of L-form, for further studies on the chemotherapy for tuberculosis.
