Pathogenesis of tubercle bacillus

1. From pulmonary tuberculosis infection may go to mediastinal group of lymph nodes and cause tuberculosis of mediastinal lymph nodes . The enlarged lymph node will compress  a lung bron chous and produce atelectasis   or there may be ulceration in bronchial wall . Discharged caseous material from the ulceration into the lumen will produce extensive lesion  .

2.  From the tuberculosis of mediastinal glands pleura may be affected through lymphatics and there wil be formation of tuberculosis pleurisy which may be accompanied by effusion , called tuberculous empyema . pericardium may be affected and produce tuberculous pericarditis .

3. From primary lesion in tonsil , cold abscess of neck may be produced .

4. From gut , tuberculous peritonitis may be produced .

5. If tuberculosis lymph node ruptures , the bacilli may enter into the vein and they will produce acute miliary tuberculosis . Tubercuar meningitis often accompanies this condition .

     6.    Through blood stream , bacilli may be localized in various organs particularly bones ,, joints               and kidneys . This will produce chronic or subacute lesion .