Wednesday, 23 October 2013

Tuberculosis and Pneumonia

Previously we have discussed about Chronic Obstructive Pulmonary Disease (COPD) which is caused mainly by smoking habits.Now we are going to continue our studies on Tuberculosis and Pneumonia.


TUBERCULOSIS


Tuberculosis (TB) is an infection caused by Mycobacterium tuberculosis which is transmitted via airborne particles. Tuberculosis is spread from person to person through tiny droplets of infected sputum that travel through the air. If an infected person coughs, sneezes, shouts, or spits, bacteria can enter the air and come into contact with uninfected people who breath the bacteria into their lungs. Tuberculosis typically attacks the lungs, but can also affect other parts of the body.


Pathophysiology


Mycobacterium tuberculosis is spread by small airborne droplets. Cell-mediated response by the body causes accumulation of activated T lymphocytes and macrophages to form a “granuloma” that limits replication of organism. Destruction of the macrophages produces early “solid necrosis.” In 2–3 weeks, this forms a soft cheesy necrotic environment; develops “caseous necrosis” establishing latency. In people with intact immunity, it generally undergoes “fibrosis” and calcification; in people with less effective immune systems, it progresses to primary progressive tuberculosis.





Tuberculin Skin Test (Mantoux)


Intradermal injection of a small amount of purified protein derived from Mycobacterium tuberculosis bacteria (PPD). The local skin reaction to PPD is used to assess an individual’s sensitivity to the tuberculin protein.


Reaction(induration) will occur within 48 to 72 hours. PPD is positive if it is :


>5 mm and HIV infection (or suspected), immunosuppressed, recent TB    contact, clinical evidence of disease on chest film.
>10 mm and age <5 years or other risk factors.
>15 mm and no risk factors.




PNEUMONIA


Pneumonia is an infection of the lungs that is caused by bacteria, viruses, fungi, or parasites. It is characterized primarily by inflammation of the alveoli in the lungs or by alveoli that are filled with fluid It is often unknown or passed on as harmless but influenza and pneumonia combined is the third highest killer in Malaysia. This is mainly because many who have the ‘flu’ feels that it will come to pass very quickly. However, if the flu is not treated properly, it could lead to more problems and in some extreme cases, it could lead to death.


Morphological classification
- Bronchopneumonia
- Lobar pneumonia





Bronchopneumonia:


  • Infants + young children and the elderly.

  • Usually secondary to other conditions associated with local and general defence mechanisms:

- viral infections (influenza, measles)
- aspiration of food or vomitus
- obstruction of a bronchus  (foreign body or neoplasm)
- inhalation of irritant gases
- major surgery
- chronic debilitating diseases, malnutrition


Lobar pneumonia:


  • Steptococcus pneumoniae.

  • Previously healthy individuals.

  • Abrupt onset.
  • Unilateral stabbing chest pain on inspiration (due to fibrinous pleurisy).




In concluding to 3 diseases aforementioned we shall take the lesson learnt and practice them in our life on how to prevent,to manage and to apply this knowledge in our future.


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