Crash Course TB + LRTI Flashcards
Describe the stages of TB
Primary: Initial infection, often in childhood, often asymptomatic
Latent: Suppressed, hangs around in foci
Post-primary: Reactivation of latent, often d.t. immunosuppression
Give 3 classes of common symptoms of TB
Constitutional: weight loss, fever, night sweats
Pulmonary: Productive cough, haemoptysis
Lymphadenitis: scrofula (cervical)
What is a ghon focus?
Competent immune system suppresses TB: macrophages form ball around TB = caseating granuloma
(Tuberculoma)
What is Miliary TB?
Disseminated haematogenous spread
Miliary seed appearance in lungs
What is Potts disease?
TB of the spine
Back pain
Vertebral collapse
Iliopsoas abscess
What is TB meningitis?
TB infiltration into the brain (Leptomeningeal enhancement)
Subacute meningitis- meningeal Sx but slow onset over a period of time
How does genitourinary TB present?
Sterile pyuria- leukocytes on urine dip but no organism detected
What is the gold standard investigation for active TB?
X3 sputum culture
Sputum culture on Lowenstein-Jensen media
What may be seen on imaging in TB?
CXR: upper lobe cavitation
CT: consolidation, Ghon focus
What is a faster test performed for active TB?
Sputum smear + Ziehl-Neelson stain for acid fast bacilli
(can also use auramine rhodamine stain)
What may be seen on histology in TB?
caseating granuloma (Haematoxylin + eosin stains)
What is the gold standard test for exposure to TB?
IGRA
Elispot/ Quantiferon
+ve if exposure (active or latent)
Does NOT cross react with BCG
Which TB test cannot distinguish between exposure to TB and BCG vaccine?
Tuberculin skin tests: Mantoux/ Heaf
Also requires 2 visits
What is the treatment for TB?
Rifampicin (6)
Isoniazid (6)
Pyrazinamide (2)
Ethambutol (2)
What drug should be given with Isoniazid? Why?
Pyridoxine (Vit B6)
To prevent peripheral neuropathy
What is the MOA of Rifampicin?
Inhibits RNA polymerase
What is the MOA of Isoniazid?
Decreased mycolic acid synthesis (part of cell wall)
What is the MOA of Pyrazinamide?
Unknown
What is the MOA of Ethambutol?
Decreased polymerisation of cell wall
Give 3 side effects of Rifampicin
Orange / red secretions
CYP450 induction
Raised transaminases
Give 2 side effects of Isoniazid
Peripheral neuropathy (B6 deficiency)
Hepatotoxicity
Give 2 side effects of Pyrazinamide
Hyperuricaemia
Hepatotoxicity
Give a side effect of Ethambutol
Optic neuritis
(Pain, vision loss, 1 eye)
Give 3 second line drugs for TB
Amikacin
Quinolones
Linezolid
Give 3 drugs to use in multi drug resistant TB
Quinolones
Aminoglycosides
Cycloserine
What is in the BCG vaccination?
Live attenuated M. Bovis
What drugs are used for latent TB?
Just Rifampicin + Isoniazid
Give 4 risk factors for mycobacterium TB
Travel
HIV
Close contacts
IVDU
Give 3 risk factors for non-tuberculous mycobacterium
> 65
Immunosuppression
Environmental exposure (water, soil)
What does mycobacterium leprae invade?
Schwann cells + Histiocytes
What are the 2 types of mycobacterium leprae?
PAUCIbacillary tuberculoid
MULTIbacillary lepromatous
Give 4 features of paucibacillary tuberculoid leprosy
Few skin lesions
Hairless plaques
Loss of sensation
Robust T cell response