TUBERCULOSE - Fisiopatologia, diagnóstico e tratamento

Summary

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis, commonly affecting the lungs but also other organs. It spreads through inhaled contaminated aerosols and often presents asymptomatically or with flu-like symptoms. Diagnosis involves clinical assessment, chest x-rays, sputum tests, and PCR. Treatment typically includes a combination of four drugs: isoniazid, rifampicin, pyrazinamide, and ethambutol. Risk factors include immunosuppression, smoking, and close contact with infected individuals. TB can also remain latent and reactivated under certain conditions. Early detection and appropriate treatment are crucial for effective management and prevention.

Takeaways

• 😀 Tuberculosis (TB) is an infectious disease caused by *Mycobacterium tuberculosis*, often affecting the lungs but can also affect other organs.
• 😀 TB spreads primarily through inhaling contaminated aerosols from an infected person who coughs, sneezes, or speaks.
• 😀 Risk factors for TB include delayed vaccination, immunosuppression (due to diseases or medications), smoking, alcoholism, homelessness, and close contact with infected individuals.
• 😀 Extra-pulmonary TB can present in several forms such as pleural, meningitis, laryngeal, and ocular, in addition to pulmonary TB.
• 😀 The primary site for TB infection is the lungs, where the bacteria thrive in the oxygen-rich environment of the alveoli.
• 😀 TB bacteria evade the immune system by preventing macrophages from destroying them, leading to the formation of granulomas and caseous necrosis in the lungs.
• 😀 Latent TB infection occurs when the immune system suppresses but does not eradicate the bacteria, which can later reactivate under weakened immunity.
• 😀 Reactivated TB tends to spread to the upper lungs, causing cavitation and leading to extrapulmonary TB through the bloodstream.
• 😀 Common symptoms of active TB include a persistent cough for over 3 weeks, evening fever, night sweats, weight loss, chest pain, and hemoptysis in severe cases.
• 😀 TB diagnosis is confirmed through clinical assessment, chest x-rays, sputum culture tests, and molecular methods like PCR, in addition to the Mantoux test for previous exposure.
• 😀 The standard treatment for TB involves a combination of four main drugs: isoniazid, rifampicin, pyrazinamide, and ethambutol, with treatment adjustments based on age and health status.

Q & A

What is tuberculosis (TB), and what causes it?

Tuberculosis (TB) is an infectious disease caused by the bacterium *Mycobacterium tuberculosis*, also known as the Koch bacillus. It typically affects the lungs but can also impact other organs in the body.

How is tuberculosis transmitted?

TB is transmitted through the inhalation of contaminated aerosols, which are released when an infected person coughs, sneezes, or speaks.

What are the common forms of extrapulmonary tuberculosis?

Extrapulmonary tuberculosis can affect several organs, including the pleura, meninges, lymph nodes, bones, kidneys, eyes, and more.

What are the risk factors for developing tuberculosis?

Risk factors include delayed vaccination, immunosuppression from diseases like HIV or medications (e.g., chemotherapy), smoking, alcoholism, homelessness, close contact with infected individuals, and advanced age or diabetes.

What is the primary site of infection for TB, and why?

The primary site of infection for TB is the lungs, specifically the alveoli, because the bacteria are aerobic and thrive in the oxygen-rich environment of the lungs.

How does *Mycobacterium tuberculosis* survive inside the body?

Once inside the lungs, *Mycobacterium tuberculosis* is engulfed by macrophages. However, the bacteria produce proteins that prevent the fusion of the phagosome and lysosome, allowing the bacteria to survive and proliferate within the macrophages.

What is granuloma formation in tuberculosis?

Granuloma formation occurs when macrophages, monocytes, and lymphocytes surround the site of infection. This forms a structure that can lead to caseous necrosis (tissue death), which may result in the formation of Ghon's focus and the later development of the Ranke complex.

What is latent tuberculosis, and how does it differ from active TB?

Latent tuberculosis occurs when the immune system suppresses the infection, and the bacteria remain dormant. Reactivation of latent TB can occur under conditions such as immunosuppression, which may lead to active TB with symptoms like cough, fever, and weight loss.

What are the primary clinical symptoms of active tuberculosis?

The main symptoms of active TB include a persistent cough lasting more than three weeks, evening fever, night sweats, weight loss, fatigue, chest pain, and in more advanced cases, hemoptysis (coughing up blood).

How is tuberculosis diagnosed?

Diagnosis is made through clinical evaluation and confirmed with tests such as chest X-rays, sputum or bronchoalveolar lavage samples (for culture, direct examination, and PCR), the Mantoux test, and histopathological examination of biopsy samples.

What is the standard treatment for tuberculosis?

The standard treatment for tuberculosis involves a combination of four drugs: Isoniazid (H), Rifampicin (R), Pyrazinamide (Z), and Ethambutol (E). The treatment lasts for six months, with an intensive phase followed by a maintenance phase.

Are there any special considerations for treating tuberculosis in pregnant women?

Yes, pregnant women should take pyridoxine alongside isoniazid to prevent neurological toxicity to the fetus. Other drug regimens may need adjustments to minimize risks to both the mother and the baby.