Tuberculosis Flashcards
What is tuberculosis?
A chronic granulomatous disease caused by Mycobacterium tuberculosis
How is it transmitted?
Inhalation of droplets infected with Mycobacterium tuberculosis.
Epidemiology
1/3 of the global population has latent TB infection
More than 95% of deaths due to TB occur in low and middle-income countries, where it is a leading cause of more mortality
1/5 of all HIV deaths are due to TB.
The incidence of TB in the UK is high compared to other Western countries (13.9/100000 in 2012)
Risk factors
Ethnic minority groups (most commonly those from sub-Saharan Africa and South Asia).
The homeless
Drug and alcohol abuse
Close contact with infected patient
Immunosuppression: HIV, chronic organ failure, Diabetes Mellitus, chronic malnutrition.
Young or old age: due to immature immune systems in the very young.
General presentation
Subacute to chronic in onset
Symptoms depend on the main site of infection, but are usually accompanied by;
night sweats
fever
weight loss
other systemic symptoms
Pulmonary presentation
Most common
Chronic cough productive of purulent sputum +/- haemoptysis.
Can get bronchiectasis, pneumonia and pleural effusions.
Pericardial presentations
Pericardial effusions
Constrictive pericarditis (usually see calcification of the pericardium on imaging)
Investigations
Can’t be stained with traditional gram stains and requires specialist stains like the Ziehl-Neelsen stain.
Management
Isoniazid, rifampicin, ethambutol, and pyrazinamide for 2 months
Isoniazid and rifampicin for a further 4 months.
Side effects of Isoniazid
Peripheral neuropathy (pyridoxine is given to prevent this)
Liver toxicity
Side effects of Rifampicin
Liver toxicity
Hepatic enzyme (p450) inducer
Turns bodily fluids red/orange colour.
Side effects of Ethambutol
Visual disturbance (colour blindness, loss of acuity etc.)
Avoid in chronic kidney disease.
CXR
Consolidation with/out cavitation
Pleural effusion
Thickening/worsening if mediasteinum by hilar/paratracheal adenopathy
Risk factors
Being of certain ethnic minority backgrounds (especially those from sub-Saharan Africa and South Asia) – the risk is highest if the patient has returned from a high-prevalence country in the last 5 years
Homelessness
Drug and alcohol abuse
Close contact with infected patient
Immunosuppression
Young or old age
Most common CXR finding in TB
Patchy pattern of opacification, sometimes described as “fibronodular”.
What type of sample is helpful in TB diagnosis?
Early morning sputum samples
What does Pyrazinamide cause?
Acute hepatotoxicity, arthralgia aka joint pain
Yellow eyes and skin
What vitamin is given to prevent peripheral neuropathy?
Pyridoxine - Vitamin B6
What should all patients who are being investigated for TB should be tested for?
HIV infection
Who should BCG vaccination be given to?
Tuberculin skin test negative (mantoux negative) contacts of patients with confirmed pulmonary and laryngeal TB, who have not been previously vaccinated and are under the age of 35 or are over the age of 35 and work in healthcare.
What is a positive mantoux test?
Apositive result would have been 5mm or more
