Bacillus Koch (Bk) or Mycobacterium tuberculosis, it is responsible for tuberculosis. Tuberculosis is making a comeback due to the appearance of multi-resistant bacterial strains. Pulmonary tuberculosis (phthisis) is the most widespread, but there are bone disorders (Pott's disease, white tumor of the knee), renal, intestinal, genital, meningeal and skin disorders (tuberculomas). Image taken from an X 1000 optical microscopy.