ABSTRACT
To study the clinical feature of pulmonary tuberculosis with sputum M. tuberculosis negative and L form of M. tuberculosis positive, the sputum of 204 patients with pulmonary tuberculosis with negative smear and culture results was cultured for L form of M. tuberculosis. A comparative study of major clinical manifestations, X ray, and therapeutic effect was carried out in 60 cases of L form positive and 144 cases of L form negative pulmonary tuberculosis. The detection rate of L form positive in patients with pulmonary tuberculosis was 29 4%. The incidence of caseous lesion and cavitation in the L form positive patients was higher than those with L form negative, and the incidence of focal absorption was higher in L form negative patients than those with L form positive. The existence of L form of M. tuberculosis suggested activity of the tuberculous lesion. The treatment of pulmonary tuberculosis must be persisted with a reasonable regimen with whole therapeutic period until L form of M. tuberculosis is eliminated from sputum.