Mycobacterium tuberculosis (TB)
They cause tuberculosis disease in humans.
Tuberculosis is respiratory disease that affects lungs and is highly infectious.
Morphology
Non motile, non capsulated, non sporing and acid fast bacilli.
Straight or slightly curved bacillus with rounded ends.
Size; 2-4 micrometre in length and 0.3-0.5 micrometre in diameter.
The staining technique is called Ziehl Neelsen's stain.
Obligate aerobic (require oxygen to grow).
Source and Modes of Transmission
Air droplets
Direct contact
Inhalation of contaminated aerosols.
Pathogenesis
Tuberculosis may affect alveoli of lung, respiratory tract.
Tuberculosis can be differenciated into two main categories.
Primarily TB
Initial infection caused by tubercle bacilli.
Nonimmune host (young child)
Ghon's complex
Hilar lymph nodes + Ghon focus; primary complex
Joint TB, Renal TB, Miliary TB
Secondary TB
(Adult type Tuberculosis)
Partially immune host (usually adult)
Lesion on apex of lungs (mainly affect upper lungs).
Cavity tuberculosis
Spread widely
Cell death (necrosis) and tissue destruction (in lungs).
Systemic or Miliary TB
Mycobacterium tuberculosis spread in blood affects organ and lungs.
It also affects with lymph nodes, bones and joints, genitourinary system, CNS and gastrointestinal system.
Treatment and Prevention
Effective treatment against TB is DOTS (directly observed treatment short course).
Active TB patient may require only one kind of anti TB drug and multi drug treatment.
Avoid sleeping in same room with someone having TB.
Avoid sending TB patient to public place like school etc.
Immunization with BCG vaccine (Bacilli Calmette Gurein).
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