All about disease tuberculosis

1. TUBERCULOSIS

2. INTRODUCTION
• Tuberculosis is a chronic Pulmonary and systemic disease
• The leading infectious cause of death worldwide
• It most commonly affects respiratory system but other parts of the
body such as gastro-intestinal tract, genitourinary tract, bones, joints,
nervous system, lymph nodes and skin may also become infected

3. CAUSATIVE ORGANISM-
• Aerobic, Slender, rod-shaped,
nonmotile, acid fast bacillus
• Length-2-10μm
• It has a lipid coat which makes it difficult
to stain, but once stained resists
decolorization by acids & alcohol

4. MODE OF TRANSMISSION
Most commonly transmitted from a
person with infectious pulmonary
TB by droplet nuclei which are
aerosolized by coughing, sneezing,
or speaking.

5. SPREAD OF TUBERCULOSIS
 LOCAL SPREAD- by macrophages
 LYMPHATIC SPREAD- bacilli may pass into lymphoid
follicles of pharynx, bronchi, intestines or regional lymph nodes
resulting – Regional tuberculous lymphadenitis
 HEMATOGENOUS SPREAD-
• Drainage of lymphatics into the venous system
• Caseous material escaping through ulcerated wall of a vein
 BY THE NATURAL PASSAGES-
• Lung lesion into pleura (Tuberculous pleurisy)
• Infected sputum into larynx (tuberculous laryngitis)
• Swallowing of infected sputum (ileocecal tuberculosis)

6. RISK
FACTORS
states such as
in Diabetes Mellitus ,
Malignancies,
pregnancy, and long
term use of steroids
etc
Overcrowding
Smoking
Malnutrition
Alcohol

7. PATHOGENESIS
Replication of mycobacteria within macrophages

8. Th1 also responsible for formation
of granulomas & caseous necrosis
Macrophages
transformed
into Epithelioid
cells
No of bacilli high, immunosuppressed,
older pt- hypersensitivity reaction
produces significant tissue necrosis in
centre of granuloma= caseous necrosis
Cheese like
consistency

9. TYPES:
I. Primary tuberculosis
II. Secondary tuberculosis
I. Pulmonary
II. Extra pulmonary: Lymph node TB
Pleural TB
Genitourinary TB
Skeletal TB
Tuberculous meningitis
Gastrointestinal TB
Miliary TB

10. Primary tuberculosis
 The infection of an individual who has not been previously infected
or immunized
 Most common site of Primary TB- Lungs
 Site of deposit: lower part of upper lobe or upper part of lower lobe
near the pleural space
 Ghon’s focus: about 2-4 weeks after the infection sensitization
develops in the host. It produces a gray white area of inflammation
with consolidation
 Ghon’s complex: combination of subpleural parenchymal lung
lesion & regional lymph node involvement

11. Secondary tuberculosis
 The infection of an individual who has been previously infected
or sensitized is called secondary, or post-primary or reinfection,
or chronic TB.
 The infection may be acquired from –
 Endogenous sources – Reactivation of dormant primary
complex.
 Exogenous sources – As fresh dose of reinfection by the
tubercle bacilli.
 It occurs most commonly in lungs in the region of Apex.
 Other sites – tonsils, pharynx, larynx, small intestine & skin.

12. CLINICAL MANIFESTATION

13. DIAGNOSIS
MYCOBACTERIAL
CULTURE
AFB
MICROSCOPY
CHEST
RADIOGRAPH MANTOUX TEST
NUCLEIC ACID
AMPLIFICATION
TECHNOLOGY

14. ACID FAST BACILLI MICROSCOPY
• A microscopic identification of acid fast bacilli in the clinical specimen
eg sputum.
• Using Ziehl neelsen stain

15. CHEST RADIOGRAPHY
• Chest radiography, or chest X-ray (CXR), is an important tool for
triaging and screening for pulmonary TB, and it is also useful to aid
diagnosis when pulmonary TB cannot be confirmed bacteriologically.

16. MYCOBACTERIAL CULTURE
• WHO recommended MGIT (Mycobacterial growth indicator tube)
• Positive after a period (10 days to 2-3 weeks)
• Tubes are read weekly until 8th weeks of incubation

17. CARTIDGE BASED NUCLEIC ACID
AMPLIFICATION TEST (CB-NAAT)
• First line diagnostic test
• Can simultaneously detect TB & Rifampin resistance in < 2 hour
• Has minimal biosafety & training requirements

18. DIAGNOSIS OF LATENT TB
 MANTOUX TEST (TUBERCULIN SKIN TESTING)
• 0.1 ml PPD (Purified protein derivative) injected intradermally in
forearm
• It is read at 48-72 hours after the injection of presence and size of an
area of induration (hardening ) of 10 mm diameter or more at the site
of injection of PPD- test positive
INTERFERON GAMMA RELEASE ASSAY (IGRA)