Lecture 9.2: Pulmonary Tuberculosis Flashcards
Mycobacterium tuberculosis staining
- Acid fast bacilli
- Stained by Ziehl-Nielsen Method
- Auramine Stain
How is TB spread?
Through Aerosol
What are the 3 Stages of TB?
- Exposure
- Latent
- Active Disease
Exposure to TB
- M. tuberculosis inhaled in the form of droplets
or aerosols - Bacilli reach the alveoli
- Macrophages launch immune response and
phagocytose (‘swallow’) the bacilli - Macrophage response may be sufficient
Latent TB
- Asymptomatic
- Macrophages contain, but don’t kill bacilli
- If initial macrophage response is insufficient to
contain the infection, the bacilli enter a phase
of exponential reproduction - Reproduction of bacilli and destruction by
macrophages enters a phase of equilibrium - Ghon focus formation (known as Ghon or
Primary complex if including a lymph node) - The bacilli are shielded from the lungs, but can
survive for extended periods - If immune system is strong Ghon complex will
heal, leaving small cavity/ scarring
What Individuals are at High Risk of infection with TB?
- Patients with history of inadequately treated TB
- The homeless
- Injecting drug users and some high risk users
(eg crack cocaine) - Health care workers with high exposure to
TB
TB should be considered in any
individual from a high risk group
presenting with…? (4)
- Unexplained cough
- Chest infection
- Febrile illness
- Resistant to simple antibiotics
Symptoms of Pulmonary Tuberculosis (5)
- Cough
- Tiredness and Malaise
- Weight Loss and Anorexia
- Fever (low grade)
- Haemoptysis
- Breathless if Pleural Effusion
Signs of Respiratory Tuberculosis (6)
- Pallor
- Fever
- Weight loss
- Finger clubbing in long standing disease
- Wheeze (possible)
- Palpable cervical lymph nodes in up to
10% of patients
What is Tuberculous Empyema?
A chronic, active infection of the pleural space that contains a large number of tubercle bacilli
Investigations for Tuberculosis (6)
- Chest X-Ray
- Sputum test for acid-fast bacilli
- Bronchoscopy
- Lavage
- Biopsies
- More detailed imaging
What can be seen on a Chest X-Ray of a TB patient?
Pulmonary Shadowing which may be:
* Patchy solid lesions
* Cavitated solid lesions
* Streaky fibrosis
Treatment of Tuberculosis
- Steriods
- Antibiotics
What is the 1st Line of Antibiotics to Treat TB?: First 2 Months (4)
- Rifampicin
- Isoniazid
- Pyrazinamide
- Ethambutol
What is the 1st Line of Antibiotics to Treat TB?: * Continuation past 4 Months (2)
- Rifampicin
- Isoniazid
What is MDR-TB?
- Multidrug-Resistant Tuberculosis (MDR-TB)
- Resistance to Isoniazid and Rifampicin
What individuals at increased risk of drug resistant TB? (5)
- Contacts of patients with drug resistant TB
- Individuals from areas where prevalence of
drug resistant TB is high - Persons whose smears remain positive after
therapy - Persons receiving inadequate treatment for
more than 2 weeks - Patients with HIV
What is cornerstone of TB control? Why?
- Contact Tracing
- Because they detect new TB cases and
prevent future cases
Concentric circle approach to contact investigations (3)
- Household
- Workplace
- Leisure
TB Prevention and Control Measures (5)
- Active case management
- TB contact screening
- New entrant screening
- Treatment of latent TB
- BCG vaccination
