Anonymous
Nov 28, 2023
Define tuberculosis, explain pathophysiology of tuberculosis, explain the clinical presentation of tuberculosis, outline diagnosis of tuberculosis, describe pharmacology treatment of tuberculosis ?
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Nov 28, 2023
Tuberculosis (TB) is a contagious bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs but can also affect other parts of the body, such as the kidneys, spine, and brain.
Pathophysiology of tuberculosis:
1. Transmission: TB is transmitted through the air when an infected person coughs, sneezes, or talks, releasing tiny droplets containing the bacteria. These droplets can be inhaled by others, leading to infection.
2. Infection: When the bacteria enter the lungs, they are engulfed by immune cells called macrophages. However, M. tuberculosis can survive and replicate within these cells, leading to the formation of small, rounded structures called granulomas.
3. Granuloma formation: Granulomas are the body's attempt to contain the infection. They consist of a central core of infected macrophages surrounded by immune cells. Over time, the granulomas may become calcified, forming small nodules visible on chest X-rays.
4. Latent vs. active TB: In some cases, the immune system is able to control the infection, leading to latent TB. Latent TB is asymptomatic and non-contagious but can become active if the immune system weakens. Active TB occurs when the bacteria multiply uncontrollably, leading to tissue damage and the spread of infection.
Clinical presentation of tuberculosis:
The clinical presentation of TB can vary depending on the site of infection. In pulmonary TB, the most common form, symptoms may include:
- Persistent cough lasting more than three weeks
- Coughing up blood or sputum
- Chest pain
- Fatigue
- Weight loss
- Night sweats
- Fever and chills
Extrapulmonary TB can present with symptoms specific to the affected organ, such as back pain in spinal TB or urinary symptoms in renal TB.
Diagnosis of tuberculosis:
1. Tuberculin skin test (TST): A small amount of purified protein derivative (PPD) is injected into the skin, and the reaction is assessed after 48-72 hours. A positive result indicates exposure to TB but does not differentiate between latent and active infection.
2. Interferon-gamma release assays (IGRAs): Blood tests that measure the release of interferon-gamma by immune cells in response to TB-specific antigens. Similar to the TST, a positive result indicates exposure to TB.
3. Chest X-ray: Used to detect abnormalities in the lungs, such as nodules or cavities, suggestive of active TB.
4. Sputum culture: A sample of sputum is collected and cultured to identify the presence of M. tuberculosis. This test confirms the diagnosis and helps determine drug susceptibility.
Pharmacological treatment of tuberculosis:
The standard treatment for TB involves a combination of antibiotics taken for several months. The most commonly used drugs include:
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
The treatment regimen typically consists of an initial phase (2 months) and a continuation phase (4-7 months). Directly Observed Therapy (DOT) is often recommended to ensure adherence to the treatment regimen and prevent the development of drug-resistant strains.
It is important to note that the specific treatment regimen may vary depending on factors such as drug resistance patterns, patient characteristics, and the presence of comorbidities.
Pathophysiology of tuberculosis:
1. Transmission: TB is transmitted through the air when an infected person coughs, sneezes, or talks, releasing tiny droplets containing the bacteria. These droplets can be inhaled by others, leading to infection.
2. Infection: When the bacteria enter the lungs, they are engulfed by immune cells called macrophages. However, M. tuberculosis can survive and replicate within these cells, leading to the formation of small, rounded structures called granulomas.
3. Granuloma formation: Granulomas are the body's attempt to contain the infection. They consist of a central core of infected macrophages surrounded by immune cells. Over time, the granulomas may become calcified, forming small nodules visible on chest X-rays.
4. Latent vs. active TB: In some cases, the immune system is able to control the infection, leading to latent TB. Latent TB is asymptomatic and non-contagious but can become active if the immune system weakens. Active TB occurs when the bacteria multiply uncontrollably, leading to tissue damage and the spread of infection.
Clinical presentation of tuberculosis:
The clinical presentation of TB can vary depending on the site of infection. In pulmonary TB, the most common form, symptoms may include:
- Persistent cough lasting more than three weeks
- Coughing up blood or sputum
- Chest pain
- Fatigue
- Weight loss
- Night sweats
- Fever and chills
Extrapulmonary TB can present with symptoms specific to the affected organ, such as back pain in spinal TB or urinary symptoms in renal TB.
Diagnosis of tuberculosis:
1. Tuberculin skin test (TST): A small amount of purified protein derivative (PPD) is injected into the skin, and the reaction is assessed after 48-72 hours. A positive result indicates exposure to TB but does not differentiate between latent and active infection.
2. Interferon-gamma release assays (IGRAs): Blood tests that measure the release of interferon-gamma by immune cells in response to TB-specific antigens. Similar to the TST, a positive result indicates exposure to TB.
3. Chest X-ray: Used to detect abnormalities in the lungs, such as nodules or cavities, suggestive of active TB.
4. Sputum culture: A sample of sputum is collected and cultured to identify the presence of M. tuberculosis. This test confirms the diagnosis and helps determine drug susceptibility.
Pharmacological treatment of tuberculosis:
The standard treatment for TB involves a combination of antibiotics taken for several months. The most commonly used drugs include:
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
The treatment regimen typically consists of an initial phase (2 months) and a continuation phase (4-7 months). Directly Observed Therapy (DOT) is often recommended to ensure adherence to the treatment regimen and prevent the development of drug-resistant strains.
It is important to note that the specific treatment regimen may vary depending on factors such as drug resistance patterns, patient characteristics, and the presence of comorbidities.
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