Tuberculosis: Lecture 3 (PDF)

TUBERCULOSIS (T.B)  Definition of T.B: Tuberculosis (TB) is a chronic specific systemic infectious disease caused by bacteria called (mycobacterium tuberculosis). The disease is characterized by formation of caseous epithelioid cell granulomas in various human organs Etiology: Causati...

TUBERCULOSIS (T.B)  Definition of T.B: Tuberculosis (TB) is a chronic specific systemic infectious disease caused by bacteria called (mycobacterium tuberculosis). The disease is characterized by formation of caseous epithelioid cell granulomas in various human organs Etiology: Causative organism: - Mycobacterium tuberculosis (human & bovine) stained with Ziehl-Nielson Stain Source of infection: Human OR animal Routes of infection: 1-Inhalation of infected droplets from patient with open TB: - commonest route - Inhaled bacilli infect the lung or the tonsil 2-Ingestion of infected milk: The bacilli infect the tonsil or the intestine 3-Inoculation via skin by handling infected materials  Risk Factors for tuberculosis Diabetes mellitus Malignant tumors chronic lung disease chronic renal failure Malnutrition Alcoholism Immune suppression states. AIDS TB bacilli flourish wherever poverty, crowding, and chronic debilitating illness exist.  Clinical presentation Coughing up blood or mucus. Night sweats. Weight loss. Tiredness. Chest pain. Pain with breathing or coughing. Fever (night)  Body reaction in TB: 1) Proliferative (cellular) tissue reaction: Usually occurs in primary TB Result in formation of TB granuloma. Usually occurs in solid organs TB granuloma - Epithelioid cells ( macrophage) - Langhans’ giant cells - Lymphocytes - Fibroblasts ± Caseation Necrosis Note: Langhan’ giant cells formed by fusion of multiple epithelioid cells or repeated division of nucleus of large epithelioid cell  5 2 4 1 3 1- epithelioid cells 2- caseation necrosis 3- Langhans’ giant cells 4- lymphocytes 5- fibroblasts TB Granuloma 2) Exudative tissue reaction:  Occurs in secondary TB  Usually occurs in serous membranes Accumulation of inflammatory fluid exudate rich in lymphocytes and fibrin Types of TB infection: 1) Primary Infection: Causes primary TB disease 2) Secondary Infection: Causes secondary TB disease  Primary Tuberculosis  Exposure: In previously unexposed (Non Immunized) individuals infection for 1st time  Age (children):  Lesion: Primary complex: with little tissue destruction  Site: - Lungs - Tonsils - Small Intestine - Skin  Fate: Depend on number of bacilli and immunity of patient 1-Complete Healing (most common) 2-Incomplete Heal 3-Rare: Progression and Complications  Secondary TB Exposure :In previously infected individuals Age: Adults Reactivation or Reinfection Lesion: Marked tissue destruction with formation - Large granuloma - Caseation - Cavity formation Site: Pulmonary OR Extra-pulmonary Fate: - Local or systemic spread - Miliary TB “tuberculin skin test”.  Fate of Tuberculosis 1-When body resistance is good: healing occurs by fibrosis 2-When body resistance is low: spread of the infection occurs:- Spread:  Direct: to adjacent tissue forming new lesion  Lymphatic: to regional lymph nodes  Blood: leading to generalized miliary TB OR isolated organ TB  Along the serous cavities as pleura  Along the natural passages  Pulmonary TB 1- Primary Pulmonary TB Consists of: - Ghon’s Focus - Lymphangitis - Lymphadenitis 2- Secondary Pulmonary TB: Endogenous source: reactivation of dormant primary complex Exogenous source Lesions of secondary pulmonary TB Apical cavitation Multiple small caseous foci in base of lung Tuberculous bronchopneumonia with consolidation Secondary Pulmonary TB Cavity  Intestinal TB 1) Primary TB: Primary Complex and tuberculous lymphadenitis 2) Secondary TB: Tuberculous ulcer in small intestine (Girdle Ulcer) 3) Hypertrophic Ileocecal TB: Large hard mass in Rt. Iliac fossa 4) TB Peritonitis: Girdle Ulcer Hypertrohic Ileocaecal TB  Bone TB Occurs in :  Vertebrae (Pott’s disease)  Long Bones (TB osteomyelitis)  Short Bones  Joints ( TB arthiritis) Vertebral TB (Pott’s Disease)  Genito-Urinary TB TB pyelonephritis  TB salpingitis  TB epididymitis Complications of Genito-Urinary TB 1) Male and Female Obstructive Infertility 2) Renal Failure (Uraemia)  TB salpingitis TB epididymitis TB of CNS: TB Meningitis Tuberculoma of cerebellum and brain stem TB meningitis Tuberculoma MCQ 1-Which type of necrosis is detected in tuberculosis: a. Enzymatic fat necrosis b. Coagulative necrosis c. Traumatic fat necrosis d. Caseation necrosis 2-Epithelioid cells are modified: A. Macrophages B. Lymphocytes C. Plasma cells D. Epithelial cells  3-Langhans' giant cells result from fusion of: A. Macrophages B. Lymphocytes C. Plasma cells D. Neutrophils 4-Ghon's focus consists of: A. Tuberculous reaction B. Non-specific inflammatory reaction C. Bilharzial reaction D. Foreign body reaction  5-Features of the tuberculous reaction include all EXCEPT: A. Epithelioid cells B. Langhans' giant cells C. Caseation D. Polymorphs 6-Types of primary tuberculous complex include all EXCEPT: A. Primary renal complex B. Primary cervical complex C. Primary intestinal complex D. Primary pulmonary complex  7-Ghon's focus occurs in which of the following organs? A. Tonsil B. Lymph nodes C. Lung D. All of the above 8-Potts diseas occure in : A. lung B. intesine C. vertebrae D. skin  9-Which of the following is commonest route of infection in human type T.B.? A.Ingestion B. Skin inoculation C.Inhalation D. Injection 10-Tuberculosis of the vertebrae is known as: A. Pott's disease B. Lupus vulgaris C. Miliary TB D. Salpingitis  Mention 1-List 3 sites of primary pulmonary Tuberculosis 2-Route of infection of TB 3- component of primary pulmonary TB