Tuberculosis Flashcards
What is tuberculosis (TB)?
Tuberculosis is a chronic infectious disease caused by Mycobacterium tuberculosis, primarily affecting the lungs but potentially any organ.
What is the primary mode of transmission for TB?
TB is transmitted via respiratory droplets from an infected person during coughing, sneezing, or speaking.
What are the main types of TB?
Types include pulmonary TB, extrapulmonary TB, and latent TB infection.
What are the common symptoms of pulmonary TB?
Symptoms include a persistent cough (lasting more than three weeks), haemoptysis, fever, night sweats, weight loss, and fatigue.
What are the symptoms of extrapulmonary TB?
Symptoms depend on the site but may include lymphadenopathy, back pain (spinal TB), abdominal pain, or neurological symptoms (TB meningitis).
What is latent TB infection?
Latent TB infection occurs when M. tuberculosis is present but inactive, causing no symptoms and being non-infectious.
What is the pathophysiology of TB?
TB infection leads to the formation of granulomas, where the immune system contains the bacteria but may reactivate under conditions of immunosuppression.
What is the aetiology of TB?
TB is caused by infection with Mycobacterium tuberculosis, a slow-growing, acid-fast bacillus.
What are the risk factors for developing TB?
Risk factors include immunosuppression (e.g., HIV), close contact with an infected person, malnutrition, homelessness, and travel to endemic areas.
What investigations are used to diagnose active TB?
Investigations include chest X-ray, sputum microscopy and culture, nucleic acid amplification tests (NAAT), and biopsy for extrapulmonary TB.
What are the chest X-ray findings in pulmonary TB?
Findings may include upper lobe infiltrates, cavitation, nodules, and hilar lymphadenopathy.
How is latent TB diagnosed?
Latent TB is diagnosed using the tuberculin skin test (TST) or interferon-gamma release assay (IGRA).
What is the tuberculin skin test (TST)?
TST measures the immune response to M. tuberculosis antigens by injecting purified protein derivative (PPD) into the skin.
What is the role of interferon-gamma release assays (IGRA) in TB?
IGRA measures the release of interferon-gamma by T-cells in response to TB antigens and is used to diagnose latent TB.
What is the management of latent TB?
Latent TB is treated with isoniazid and/or rifampicin to prevent progression to active TB.
What is the standard treatment regimen for active TB?
Active TB is treated with a 6-month course of antibiotics: 2 months of isoniazid, rifampicin, pyrazinamide, and ethambutol (intensive phase), followed by 4 months of isoniazid and rifampicin (continuation phase).
What are the side effects of isoniazid?
Side effects include hepatotoxicity, peripheral neuropathy (prevented with pyridoxine), and rash.
What are the side effects of rifampicin?
Side effects include hepatotoxicity, orange discolouration of body fluids, and drug interactions.
What are the complications of untreated TB?
Complications include extensive lung damage, respiratory failure, extrapulmonary spread (e.g., TB meningitis), and death.
What is multidrug-resistant TB (MDR-TB)?
MDR-TB is resistant to at least isoniazid and rifampicin, requiring second-line drugs for treatment.
What vaccinations can prevent TB?
The Bacillus Calmette-Guérin (BCG) vaccine can prevent TB in high-risk populations.
What are the indications for BCG vaccination?
Indications include infants in areas with high TB prevalence or those with household contacts of TB.
What public health measures help control TB?
Measures include contact tracing, isolation of infectious patients, vaccination, and prompt treatment of active and latent TB.
What are the differential diagnoses for pulmonary TB?
Differential diagnoses include lung cancer, pneumonia, sarcoidosis, and fungal infections.
What is the global burden of TB?
TB is a leading cause of death worldwide, particularly in low- and middle-income countries, with millions of cases annually.
