Infectious Diseases Flashcards
What is active TB?
Inadequate containment by immune system
Can be primary infection or re-activation of latent infection
What is latent TB?
Infection without disease
Containment via granuloma formation
What are risk factors for re-activation of TB?
Immunosuppression - HIV, organ transplant
Malnutrition
Homelessness
How is latent TB identified?
Interferon gamma release assay/QuantiFERON - measures release of interferon-gamma from T cells when exposed to TB antigen. Pre-exposed cells => greater release
Mantoux test
Who is screened for TB?
Immigrants from areas with high prevalence
Health care workers
HIV +ve
Pts starting immunosuppressants
How does pulmonary TB present?
Chronic cough
Haemoptysis
Pleural effusion
What are systemic features of TB?
Fever
Night sweats
Weight loss
What is miliary TB?
Haematogenous dissemination
Formation of discrete foci of granulomatous tissue throughout lung
What investigations are done in TB?
CXR
Sputum smear - Ziehl-Neelsen stain, identifies AFB
Sputum culture
If extra-pulmonary get biopsy to do stain
HIV testing
What CXR changes are seen in TB?
Cavitations, opacities in upper lobes
Bilateral hilar lymphadenopathy
Signs of miliary TB
What is the management of TB?
Rifampicin, isoniazid, pyrazinamide, ethambutol
2 months of all, then 2 months of rifampicin and isoniazid
Steroids if CNS/pericardial involvemement
What are side effects of rifampicin?
Orange body secretions
Altered liver function
Enzyme inducer => warfarin, oestrogen
What are side effects of isoniazid?
Inhibits production of pyridoxine (vit b6) => peripheral neuropathy
Hepatitis
What are side effects of pyrazinamide?
Hepatotoxicity
What are side effects of ethambutol?
Colour blindness
Dec visual acuity
Optic neuritis
