Tuberculosis

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis. The primary mode of transmission is airborne, meaning that the bacteria spread through the air from person to person. When a person with active TB disease in their lungs coughs, sneezes, speaks, or sings, they release microscopic droplets containing TB bacteria into the air. People nearby can inhale these droplets and become infected. Factors that increase the risk of contracting TB include close contact with an infected person, living or working in crowded or poorly ventilated conditions, weakened immune systems (due to conditions like HIV/AIDS, diabetes, or malnutrition), and certain medical treatments that suppress the immune system.

Symptoms of Tuberculosis

Symptoms of tuberculosis can vary depending on whether the disease is latent or active and which part of the body is affected. 

Common Symptoms of Active TB:

• Persistent cough lasting more than three weeks
• Coughing up blood or sputum (phlegm)
• Chest pain
• Unintentional weight loss
• Fatigue and weakness
• Fever and chills
• Night sweats
• Loss of appetite

Symptoms of Extrapulmonary TB

• Swollen lymph nodes (especially in the neck)
• Bone and joint pain
• Blood in the urine (if the kidneys are affected)
• Headache and confusion (if the brain is affected)
• Abdominal pain (if the gastrointestinal tract is affected)

Diagnosis of Tuberculosis

Diagnosing tuberculosis involves several methods to detect the presence of Mycobacterium tuberculosis bacteria and assess the extent of the disease. 

Diagnosis Methods

Tuberculin Skin Test (TST)

A small amount of purified protein derivative (PPD) is injected under the skin of the forearm. After 48-72 hours, the injection site is examined for a reaction, which indicates TB infection.

Interferon-Gamma Release Assays (IGRAs)

Blood tests that measure the immune system’s response to TB bacteria. These tests are more specific than the TST and do not require a follow-up visit.

Chest X-Ray

Imaging test that helps visualize abnormalities in the lungs that may suggest TB infection, such as infiltrates or cavities.

Sputum Smear Microscopy

Examination of a patient’s sputum under a microscope to detect the presence of TB bacteria. This test is particularly useful for diagnosing pulmonary TB.

Sputum Culture

Sputum samples are cultured in a laboratory to grow and identify TB bacteria. This method is more accurate but takes several weeks to yield results.

Nucleic Acid Amplification Tests (NAATs)

Molecular tests that detect the genetic material of TB bacteria in sputum samples. These tests are rapid and highly sensitive.

Biopsy

In cases of extrapulmonary TB, a biopsy of the affected tissue (such as lymph nodes or bone) may be performed to confirm the diagnosis.

Treatments of Tuberculosis

Treatment for tuberculosis involves a combination of antibiotics taken over an extended period. This is crucial to ensure the complete eradication of the bacteria and to prevent the development of drug-resistant TB.

Isoniazid: Isoniazid is a first-line antibiotic used in the treatment of TB. It is usually taken daily for six to nine months and is effective in killing actively growing TB bacteria.

Rifampicin: Rifampicin is another first-line antibiotic commonly used in TB treatment. It is taken daily for at least six months and works by inhibiting bacterial RNA synthesis, thus killing TB bacteria.

Ethambutol: Ethambutol is often included in the initial phase of TB treatment to prevent the development of drug resistance. It works by inhibiting the synthesis of the bacterial cell wall.

Pyrazinamide: Pyrazinamide is a key drug in the initial phase of TB treatment, typically taken for the first two months. It helps to kill dormant TB bacteria that are not actively dividing.

Streptomycin: Streptomycin is an aminoglycoside antibiotic used in certain cases of TB, particularly when there is resistance to other drugs. It is usually administered by injection.

Bedaquiline: Bedaquiline is a newer antibiotic used to treat multidrug-resistant TB (MDR-TB). It works by inhibiting the enzyme ATP synthase, which TB bacteria need to generate energy.

Linezolid: Linezolid is an antibiotic used to treat MDR-TB and extensively drug-resistant TB (XDR-TB). It inhibits bacterial protein synthesis, making it effective against resistant strains of TB.

Delamanid: Delamanid is another newer drug used for MDR-TB. It works by inhibiting the synthesis of mycolic acids, essential components of the bacterial cell wall.

Levofloxacin: Levofloxacin is a fluoroquinolone antibiotic used in the treatment of drug-resistant TB. It inhibits bacterial DNA synthesis, preventing the bacteria from replicating.

Clofazimine: Clofazimine is used as part of combination therapy for MDR-TB. It has anti-inflammatory properties and works by binding to bacterial DNA.

Effective treatment of TB requires strict adherence to the prescribed medication regimen to prevent the development of drug resistance and ensure successful recovery. Monitoring and managing side effects are also essential components of TB treatment.