Tuberculosis
Contents
Tuberculosis
• Etiology
• Pathophysiology
• Preventive measures
Objectives
At the end of this Lecture, student will be able to
• Discuss the etiology of tuberculosis
• Explain the pathophysiology of tuberculosis
Tuberculosis
• Chronic granulomatous disease caused by Mycobacterium tuberculosis
• Usually affects lungs
• Organism is a strict aerobe and thrives best in tissues with high oxygen tension such as in the apex of the lung
Risk factors
• Person’s whose immune system is weakened (HIV infected people)
• Alcohol or drug abuse
• Diabetic persons
• Regular contact with TB infected persons
• Multidrug resistance TB occurs if Patients do not complete the course of antibiotic therapy
Symptoms of Tuberculosis
• Persistent cough for 15 days
• Fever, Chest pain, haemoptysis, dyspnoea, night sweats, tiredness, loss of apetite, rapid weight loss, swollen glands, signs of pneumonia
• Joint pain
• TB of GIT – abdominal pain
• TB in brain – altered mental status, headache, confusion and coma
• Weakness due to anemia, backpain, paralysis
Mode of transmission of Tuberculosis
• Inhalation of organisms present in fresh
cough droplets or in dried sputum from an open case of pulmonary tuberculosis
• Ingestion of the organisms
• Development of tonsillar or intestinal tuberculosis
• Mode of infection of human tubercle bacilli
• Ingestion of bovine tubercle bacilli from milk of diseased cows
• Inoculation of the organisms into the skin
• Transplacental route
• Development of congenital tuberculosis in foetus from infected mother
• Rare mode of transmission
Spread of tuberculosis
• Local spread: macrophages carrying the
bacilli into the surrounding tissues
• Lymphatic spread:
• Infection of lymphoid tissues
• Bacilli pass into lymphoid follicles of pharynx, bronchi, intestines or regional lymph nodes
• Regional tuberculous lymphadenitis
• Haematogenous spread
• Result of tuberculous bacillaemia
• Drainage of lymphatics into the venous system or due to caseous material
• Escaping through ulcerated wall of a vein
• Millet seed-sized lesions in lungs, liver, kidneys, bones and other tissues
• Known as miliary tuberculosis.
Primary disease
• An initial infection with bacilli
• In areas of high TB prevalence – this form of
disease is often seen in children
• Frequently localized to the middle and lower
lobes of the lungs
• Lesions – calcified nodule (Ghon lesion)
Secondary TB
• Adult type, reactivation, or secondary TB –
endogenous reactivation of latent infection
• Localized to the apical and posterior segments
of the upper lobes
• Oxygen consumption favors mycobacterial growth
• Extent of lung parenchymal involvement varies
greatly, from small infiltrates to extensive cavitary disease
Summary
• Tuberculosis is an granulomatous and infectious disorder that will typically occur in the lung called pulmonary tuberculosis and if it occurs for other organs it’s called extra pulmonary Tuberculosis
• Tubercle bacillus or Koch’s bacillus or Mycobacterium tuberculosis causes tuberculosis in the lungs and other tissues of human body by hematogenous,
lympahtic or transplacental route
Also, Visit: Pathophysiology Notes