1. None spore forming Gram Psitive Bacteria Mycobacterium Tuberculosis

2. Mycobacterium tuberculosis is the second most common infectious cause of death in adults worldwide (HIV is the most common). The human host serves is the natural reservoir for M. tuberculosis. The ability of the organism to efficiently establish latent infection has enabled it to spread to nearly one-third of individuals worldwide. Approximately 8 million new cases of active TB disease occur each year, leading to about 1.7 million deaths. The disease incidence is magnified by the concurrent epidemic of human immunodeficiency virus (HIV) infection.

3. NATURAL HISTORY OF INFECTION Inhalation of M
NATURAL HISTORY OF INFECTION Inhalation of M. tuberculosis and deposition in the lungs leads to one of four possible outcomes: ●Immediate clearance of the organism ●Latent infection ●Immediate onset of active disease (primary disease) ●Onset of active disease many years following exposure (reactivation disease)

4. Morphology of Mycobacterium tuberculosis
Straight, slightly curved Rod shaped 3 x 0.3microns
May be single, in pairs or in small clumps
On conditions in growth appears as filamentous, club shaped, or in Branched forms.

5. How tuberculosis spreads
Tuberculosis (TB) is a contagious disease. Like the common cold, it spreads through the air. Only people who are sick with TB in their lungs are infectious. When infectious people cough, sneeze, talk or spit, they propel TB germs, known as bacilli, into the air. A person needs only to inhale a small number of these to be infected.

6. Tuberculosis spread by Respiratory route

7. Tuberculosis highly Communicable Disease.
Someone in the world is newly infected with TB bacilli every second.
Overall, one-third of the world's population is currently infected with the TB bacillus.
5-10% of people who are infected with TB bacilli (but who are not infected with HIV) become sick or infectious at some time during their life. People with HIV and TB infection are much more likely to develop TB.

8. Pathology and Pathogenesis of Tuberculosis
Source of Infection – Open case of Pulmonary Tuberculosis.
Every open case has potential to infect 20 – 25 healthy persons before cured or dies
Coughing , Sneezing, or Talking.
Each act can spill 3000 infective nuclei in the air
Infective particles are engulfed by Alveolar Macrophages.

9. Spread of Tuberculosis

10. Generation of Droplet Nuclei
One cough produces 500 droplets
The average TB patient generates 75,000 droplets per day before therapy
This falls to 25 infectious droplets per day within two weeks of effective therapy
The most important mechanism by which infectious droplets are produced is coughing. However, any vigorous expiratory maneuver such as sneezing, singing, talking or even quiet breathing, can also produce infectious droplets.
One of the ways in which treatment reduces infectiousness is to rapidly decrease cough.
[Image Credit: Andrew Davidhazy, School of Photo Arts and Sciences/RIT.]

11. Dr.T.V.Rao MD

12. Predisposing Factors Genetic basis, Age Stress, Nutrition,
Co existing infections Eg HIV

13. Mechanisms of Infection
Mycobacterium do not produce toxins.
Allergy and Immunity plays the major role.
Only 1/10 of the infected will get disease.
Cell Mediated Immunity plays a crucial role.
Humoral Immunity – not Important.
CD4 Cell plays role in Immune Mechanisms.

14. Mechanisms of Infection
Within 10 days of entry of Bacilli clones of Antigen specific T Lymphocytes are produced
Can actively produce Cytokines,
Interferon γ which activate Macrophages form cluster or Granuloma

16. Tubercle with Caseous Necrosis
Giant cells
Tubercle bacilli
Partially activated
macrophage
Lymphocyte
Fully activated

17. Basis of Tubercle formation.
Tubercle is a Avascular granuloma Contain central zone of giant cells with or without caseation and peripheral zone of Lymphocytes and Fibroblasts.
Produce lesions may be Exudative or Productive

18. Diagram of a Granuloma
NOTE: ultimately a fibrin layer develops around granuloma (fibrosis), further “walling off” the lesion.
Typical progression in pulmonary TB involves caseation, calcification and cavity formation.

19. Tubercle discharging
Bronchial tree
TNF- a
Dr.T.V.Rao MD

20. CLASSIFICATION — Within the genus Mycobacterium, four groups of human pathogens can be delineated on the basis of microbiologic, clinical, and epidemiologic characteristics
The M. tuberculosis complex
M. leprae
Slowly growing nontuberculous mycobacteria
(M. kansasii)
Rapidly growing mycobacteria (M. fortuitum)

21. Why they are Acid Fast
The character of Acid fastness is due to presence of Unsapnofiable wax ( My colic acid and semi permeable membrane around the cell)

22. MTB : Cultural characters
Grow slowly. Generation time hrs
Colonies appear after 2 weeks or at 6-8 weeks
MTB - Obligate aerobe
MTB grows more luxuriantly (eugonic) than M. bovis (dysgonic).
Addition of 0.5% Glycerol supports growth of human strains. No effect or inhibitory effect on bovine strains.

23. Culturing Acid Fast Bacilli
Slow to grow ,
Generation time is 14 – 15 hours
> 2 weeks minimal required period
Grows at 370c do not grow below 250c
Ph between 6.4 to 7.0

24. Eight Week Growth of Mycobacterium tuberculosis on Lowenstein-Jensen Agar
Dr.T.V.Rao MD

25. Nature of Media Used Helps the growth needs
Solid Medium is commonly used
Lowenstein Jensen’s medium
Petrangini
Middle brook medium

26. Lowenstein Jensen’s Medium
Contain coagulated egg
Mineral salt solution
Asparagine's
Malachite green
Agar

27. Poverty and Crowded living spreads Tuberculosis
Dr.T.V.Rao MD

28. Thank you