2 Long, slender bacilli with branching filamentous forms. Obligate pathogens, Saprophytic and Opportunistic. Lipid-rich waxy cell wall. Responsible for Chronic granulomatous lesions. In 1882 Robert Koch :
3 CLASSIFICATION Tubercle bacilli: a. Human : M. tuberculosis, M. africanum b. Bovine : M. bovis c. Murine : M. microti. d. Avian : M. avium. e. Cold blooded: M.marinum Lepra bacilli: a. Human : M. leprae b. Rat : M. leprae murium
4 3. Mycobacteria from skin ulcers. M. ulcerans, M. balnei, M. buruli. 4. Atypical Mycobacteriae: 5. Jhone’s bacillus: M. para tuberculosis. ( Chronic specific enteritis in cattle ) 6. Saprophytic Mycobacteria. M. butyricum. M. smegmatis, M.stercoris.
5 Straight / slightly curved rods with occasional branching. 3 x0.3µm. Non motile, Non-capsulated, Non- sporing Cell wall structure
Lipid-rich waxy cell wall
Acid fast ,alcohol fast.
Slow growth in culture
Resistant to antiseptics
Clumps in liquid medium.
Acid fast staining
Ziehl - Neelsen method. Kinyoun’s method.
Gram staining : No use.
LIKE SERPENTINE CORDS.
6 CULTURAL CHARACTERS Doubling time 14 – 15 hrs. Optimum temperature 37º C . (No growth < 25º C & > 40º C) 1. Egg media: Lowenstein – Jensen medium. Dorset egg medium. L J medium : 2 - 6 weeks Sterilized by Inspissation. Glycerol, asparagines. Malachite green as selective agent. Egg albumen as solidifying agent. 2. Blood (Tarshis medium ). 3. Serum (Loeffler’s serum slope ).
7 LIQUID MEDIA : Dubo’s medium. Middle –Brook medium. Bactec 12B medium. Uses : Sensitivity tests. Chemical tests. Preparation of antigens & vaccines.
8 GROWTH : M. tuberculosisM. bovis. Heaped up & luxuriant Sparse (dysgonic) growth. (eugonic) Dry, rough, tuff Moist, smooth flat buff colour. with white colour. 0.5 % glycerol Sodium pyruate ( L J medium)( Stone brink's medium ) Grows on surface. Grows as band few mm. (Aerobe) below the surface (Anaerobe)
9 Growth on Lowenstein- Jensen (LJ) medium. SENSITIVITY
Tincture of Iodine
10 BIOCHEMICAL TESTS
Nitrate reductase positive.
Aryl sulphatase negative
Resistant to thiophen – 2 – Carboxylic acid hydrazide (TCH) which is related to INH.
1. To differentiate M.tuberculosisfrom M. bovis and Atypical mycobacteriae 2. To identify virulent & avirulent strains.
1.Cell wall insoluble polysaccharide antigens. Group specificity. 2.Cytoplasmic soluble protein antigens. Type specificity. TUBERCULIN PROTEIN
12 PATHOGENESIS: Pulmonary alveoli. Taken up by Macrophages & multiplied. Primary site of infection in lower part of upper lobes / upper part of lower lobes - Ghon’s focus. With hilar lymphadenopathy (PRIMARY COMPLEX) Initiates CMI Inhalation Droplets, aerosols from patients & Cough spray from Animal
13 Pathogenesis Contd……: Activation of specific T - cells (cytokines, gamma interferon production) DTHImmune response Formation of Tubercle. Activate macrophages ( Avascular granuloma) (Inhibits multiplication). Consumes much of O2 & produces acidosis. Most of the bacilli are killed. Resolution Some remain dormant. Protective Immunity. Post – primary disease.
14 Avascular granuloma Central Zone of Caseous (Cheese like ) material dead T &B cells and macrophages surrounded by different types of cells. IL 2: Proliferation of Ag-primed T cells Gama INF: Enhances activity of macrophages & NK cells. TNF-ά (Cachectin): Induces cytokine secretion in the inflammatory area. Muscle wasting, fever.
15 Expanding large Avascular granuloma (Tuberculomata). Erodes through wall of bronchus. Liquified contents discharged into the bronchus. CAVITY formed. Shelter for huge number of bacilli. Gets access to sputum Open case of TB. ( Transmissible case of TB )
16 2. Ingestion : Unpasteurised milk Primary complex in tonsils, cervical LN & Ileocaecal region ( Mesenteric LN ). Initiates CMI. 3. Inoculation : Rare ( Occupational in anatomists , pathologists ). Skin with involvement of regional LN. Prosector’s warts.
17 Clinical features
Persistent dry cough
Sweating at night, in spite of cold
Shortness of breath
Coughing up blood
18 Progression of disease Lesion breaks down Bacilli released and spread Through blood & lymph Spleen, liver, lungs, BM, Kidney, Adrenal glands, Eyes ,CNS . Chronic pneumonitis, Tuberculous osteomyelitis, Tuberculous meningitis Milliary tuberculosis
21 IMMUNITY & DTH (Allergy): CMI is useful. 6 – 8 weeks after infection : Tuberculin test reaction occurs. Described by Koch’s Phenomenon.
22 INJECTED with TU antigen SC 4-6 wks later. GUINEA PIGINFECTEDWITH TB BACILLI. After 1 – 2 days Indurated lesion at the site of Injection. Undergoes rapid necrosis. Shallow ulcer Heals rapidly without involvement of regional lymph nodes. Koch’s phenomenon
23 TUBERCULIN TEST Clemens von Pirquet (1907) : OT. Seibert (1939) : Purified Ag by Ammonium sulphate fractionation (PPD). Strength of PPD expressed in TU. A measured amount ( 5 – 10 TU ) is injected.
24 MONTOUX TEST 5 TU of PPD injected Intradermally in Flexor aspect of forearm. (Tuberculin syringe) No scratch on itching. Read after 48 - 72 hrs . Induration. Only erythema not considerable. >10mm - Significant
25 EPIDEMIOLOGY Transmissionamong households. Dusty environment , Hill dwellers (Silica) . Low Socio-economic status, Malnutrition. (A barometer of social welfare ) Asia & sub- Saharan nations are more prone.
26 Every minute someone dies of TB in India. >5,00,000 die every year. If there is no effective action, 5 million may die of TB in the next few years. 1.8 million new cases every year. India has the highest burden of the disease in the world. Dr L S Chauhan, Director General (TBCP)Nov’ 6 2006 India Together
27 RNTCP or Revised National Tuberculosis Control Program is the State-run Tuberculosis Control Initiative of the Government of India . It incorporates the principles of Directly observed treatment Short course (DOTS) - the global TB control strategy of the WHO. The program provides free of cost, quality Anti-Tubercular drugs through the PHCsand the private-sectorDOTS-providers.
28 The DOTS strategy is cost-effective and is today the international standard for TB control programmes. To date, more than 180 countries are implementing the DOTS strategy. India has adapted the DOTS strategy in various parts of the country since 1993, with excellent results, and by March 2006 nationwide DOTS coverage has been achieved.
29 Rapid DOTS expansion in India In 2000 , 2001 and 2002 more than a million patients were treated in this way in India. As a result nearly 2,00,000 lives were saved. Extensively drug-resistant TB (XDR-TB) in > 30 countries since 2006, multidrug-resistant TB (MDR-TB) and XDR-TB have recently become a particular focus of international concern.
30 LAB. DIAGNOSIS 1.Primary TB If productive: Sputum If not productive: Bronchial washings/ brushings/ biopsy. 2.Secondary/Post Primary TB a. CSF b. Pleural fluid c. Synovial fluid.
31 Decontamination & concentration methods. 1. Petroff’s method: Equal volumes of sputum & 4% NaoH Keep at 37º C with intermittent shaking for 20 mts. Neutralized with (Potassium dihydrogen orthophosphate). Centrifuge at 3000 rpm for 30mts. Deposit: Microscopy Culture.
32 2.Non centrifugation & Non neutralization method: Equal volumes of sputum + 2% Cetrimonium bromide & 4% NaoH 5 mtsculture. Materials used for Homogenization: a. Diluted acids ( 6% H2 SO4, 3 % HCl ) b. N-Acetyl Cystein with NaoH. c. Pancreatin. d. Cetrimide.
33 MICROSCOPY Minimum of 10,000 bacilli / ml of sputum. 100 fields must be examined . 1.Kinyoun’s method 2.Ziehl - Neelsen technique. 3.Fluorescent dye technique. Auramine Phenol, AuramineRhodamine dye.
34 INTERPRETATION 3-9 bacilli in entire smear:1+ or more /entire smear: 2+ 10 or more / field: 3+ Beaded forms: M.tuberculosis Uniform: M.bovis
35 2. CULTURE : A. Conventional method: Concentrated sample. L -J medium 35 - 37º C. Inspect weekly up to 8 weeks. B. Rapid diagnosis of growth: Bactec system: Radiometric detection of CO2.
36 C. Fluorescent dye methods Activation of fluorescent dye by the released CO2 3.Nucleic acid technology: 1.Nucleic acid probes : Not sensitive 2.PCR: Conventional PCR is best. 4. Tuberculin test: 5. Serology: PHA . Ig M, Ig G and Ig A estimation ( Specific but not sensitive tests).
37 X-Ray findings of pulmonary TB Primary complex in the hilar region
38 PREVENTIVE MEASURES 1.General measures: Adequate nourishment. Good housing . Health education. Contact tracing. 2.Chemoprophylaxis: INH
39 The basic methods of preventing TB transmission
Preventing the release of the
Preventing the inhalation, through
Use of high-efficiency particulate
air (HEPA) filters in the entry ways.
Chemoprophylaxis for suspected
40 3.IMMUNOPROPHYLAXIS:BCG Live attenuated vaccine. Bovine strain (Danish 1331 by 239 serial subcultures on Glycerin bile potato medium). Freeze dried vaccine (Normal saline). At birth / within 6 weeks of age. Intradermally over deltoid region. Dose : 0.1 mg in 0.1 ml. volume. Efficacy : 0 – 80 %.
41 EVENTSAFTERINJECTION : Papule within 2 – 3 weeks. Enlarges to 4 – 8 mm within 5 weeks. Subsides and broken into ulcer. Heals spontaneously with scar formation within 6 - 12 weeks. Complications: Local : Abscess, indolent ulcer, Keloid. Regional: Local lymphadenopathy. General : Fever, mediastinal adenitis,
42 CONTRAINDICATIONS Generalized eczema. Infective dermatosis. Hypo gamma globulinaemia. Immunodeficiency. Protection not absolute after vaccination, May suffer with milder form of disease.
43 ANTI TUBERCULOSIS DRUGS First-line: Rifampicin (R) Pyrazinamide (Z) Isoniazid ( H ) Ethambutol Second-line: Amikacin, Capreomycin, Kanamycin and Ofloxacin, Streptomycin (Since 2005)
44 SHORT COURSE CHEMOTHERAPY Drugs Initial Drugs Continuation phase phase Standard regime. RHZ 2M RH 4M Intermittent regime. RHZ 2M R3 H3 4M RHZ 2M R2 H2 4M R3H3Z3 2M R3 H3 4M Incase of high incidence of initial drug resistance. RHZE 2M RH 4M RHZS 2M RH 4M
45 The challenge to Medical profession is to be prepared for all infectious diseases that may affect the practice.