Tuberculosis is caused by the bacterium Mycobacterium tuberculosis, a slow-growing, acid-fast bacillus. It primarily affects the lungs but can involve other organs. The unique cell wall of Mycobacterium tuberculosis contains mycolic acid, which provides resistance to standard stains and antibiotics, requiring special staining techniques like the Ziehl-Neelsen stain for diagnosis. Its ability to survive within macrophages leads to chronic granulomatous inflammation, a hallmark of tuberculosis. Effective treatment targets this bacterium specifically, highlighting its critical role in the disease.

Reference: Robbins Basic Pathology, Kumar et al., 10th Edition.