Микобактериальные заболевания
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Calcified Granulomatous Lung Lesions Contain Abundant Mycobacterium tuberculosis Components

Tadatsune Iida, Keisuke Uchida, Nilufar Lokman, Asuka Furukawa, Yoshimi Suzuki, Toshio Kumasaka, Tamiko Takemura, Hiroshi Kawachi, Takumi Akashi and Yoshinobu Eishi

Mycobacterium tuberculosis can survive for a long time in the body of a healthy host, causing no symptoms after primary infection. Years or decades later, M. tuberculosis can be reactivated in some carriers, leading to symptoms of post-primary tuberculosis. During the asymptomatic period, M. tuberculosis is believed to survive in old foci of infection, yet these foci are uniformly negative by culture and acid-fast staining, which are conventional methods to detect mycobacteria. The precise location and amount of M. tuberculosis in these foci, therefore, are not well understood. Here we report that granulomatous lesions with calcification, a well-known characteristic of old tubercles, contained considerable amounts of M. tuberculosis genomes and cell wall components. These calcified lesions exhibited little inflammation but all were positive for M. tuberculosis by real-time polymerase chain reaction and by immunohistochemistry with a novel monoclonal antibody against lipoarabinomannan, a cell wall component of mycobacteria. We found many lipoarabinomannan-containing granules in the necrotic areas of the lesions that were negative by Ziehl-Neelsen staining but included some bacillus-like structures. The risk of reactivation of latent tuberculosis from these calcified granulomatous lung lesions should be considered.