Tuberculosis Flashcards
What is the global distribution of tuberculosis (TB) and its impact on the UK?
Global distribution:
TB remains a major global health issue, with the highest burden in South Asia, sub-Saharan Africa, and Eastern Europe.
The World Health Organization (WHO) reports over 10 million cases globally per year.
Impact on the UK:
The UK sees declining TB rates but still reports significant numbers of cases, especially in urban areas and among immigrants from high-burden countries.
The UK has a national TB strategy to reduce incidence, with continued focus on early diagnosis, treatment, and contact tracing.
What is the pathogenesis of tuberculosis in its primary, post-primary, and fibrocaseous forms in the lung?
Primary Tuberculosis:
Inhalation of Mycobacterium tuberculosis leads to initial infection, typically in the lower lungs.
The body forms a granulomatous response with caseation necrosis around the infection, leading to primary lesions (Ghon focus).
Post-primary (Reactivation) Tuberculosis:
Reactivation of dormant bacteria in individuals with previous infection, commonly occurring in the upper lobes due to reduced immune function.
Cavitary lesions form as bacteria proliferate and cause necrosis.
Fibrocaseous Tuberculosis:
Chronic form of post-primary TB characterized by fibrosis and cavitation of lung tissue, often with caseous material in the cavities.
This can lead to chronic symptoms and lung damage.
What is the histopathology of tuberculosis?
Granulomatous inflammation: Characterized by epithelioid macrophages, Langhans giant cells, and lymphocytes.
Caseous necrosis: Central area of necrosis within granulomas, often described as “cheese-like.”
Tuberculous abscess formation in advanced disease.
Fibrosis in chronic cases, leading to cavitation.
What are the common clinical presentations of tuberculosis (TB)?
Pulmonary TB:
Chronic cough (lasting more than 3 weeks), often productive with blood-streaked sputum.
Night sweats, fever, and weight loss (constitutional symptoms of “TB triad”).
Chest pain and hemoptysis (in advanced disease).
Extrapulmonary TB:
Can affect various organs like lymph nodes (scrofula), spine (Pott’s disease), genitourinary system, or the central nervous system (meningitis).
What are the major groups of antituberculous drugs, their pharmacological profiles, side effects, and their practical application in the management of tuberculosis?
First-line drugs:
Isoniazid: Inhibits mycolic acid synthesis. Hepatotoxicity, peripheral neuropathy (prevent with pyridoxine).
Rifampicin: Inhibits RNA polymerase. Hepatotoxicity, orange-red urine, drug interactions.
Pyrazinamide: Inhibits mycobacterial membrane synthesis. Hepatotoxicity, arthralgia.
Ethambutol: Inhibits cell wall synthesis. Optic neuritis, color blindness.
Second-line drugs:
Used for drug-resistant TB. Includes fluoroquinolones, amikacin, capreomycin, and others.
Associated with more toxicities and longer treatment durations.
Practical Application:
Standard regimen: Typically involves a combination of 4-drug therapy (INH, rifampin, pyrazinamide, and ethambutol) for initial phase.
Treatment duration is generally 6-9 months, extended for drug-resistant TB.
What are the public health duties of doctors managing cases of tuberculosis (TB)?
Diagnosis and reporting:
Timely diagnosis and reporting of TB cases to public health authorities for contact tracing and surveillance.
Ensuring treatment completion:
Directly Observed Therapy (DOT): Supervised medication administration to ensure adherence to the treatment regimen and prevent drug resistance.
Infection control:
Isolation of infectious patients (especially during the infectious phase) to prevent transmission.
Testing and treatment of close contacts to prevent outbreaks.
Preventive measures:
BCG vaccination in high-risk populations.
Screening of high-risk individuals (e.g., those with HIV, healthcare workers, close contacts).
