Resp Flashcards
primary, secondary and miliary TB
primary: encapsulated in hilar lymph nodes, Ghon focus macrophages contain it
secondary: goes to apices of lungs
miliary: disseminated in bloodstream
Secondary TB sites
Lungs (most common)
central nervous system (tuberculous meningitis - the most serious complication)
vertebral bodies (Pott’s disease)
cervical lymph nodes (scrofuloderma)
renal
gastrointestinal tract
Systemic TB symptoms
night sweats
fever
weight loss
Lung TB symptoms
Chronic cough productive of purulent sputum +/- haemoptysis.
Can get bronchiectasis, pneumonia and pleural effusions.
CNS TB symptoms
TB meningitis or tuberculoma
Headache
Meningism
Focal neurological signs
Decreased consciousness
Genitourinary TB symptoms
Second most affected organ system outside of the lungs.
Causes ‘sterile’ pyuria, kidney pathology, abscesses, salpingitis and infertility, epididymo-orchitis.
MSK TB symptoms
Arthritis
Osteomyelitis
Psoas abscess
Pott’s Disease of the Spine.
skin TB symptoms
erythema nodosum
TB investigations
CXR - upper lobe cavitation is the classical finding of reactivated TB
bilateral hilar lymphadenopathy
Sputum samples for culture and sensitivity testing (at least three needed - may need to consider lavage or sputum induction if cannot produce)
Samples from non-pulmonary sites: may need biopsy and needle aspiration
Samples are stained with Ziehl-Neelsen or Auramine staining for direct microscopy
IGRA test
Interferon-Gamma Release Assays (IGRAs) - cannot tell difference between latent or active TB, and not useful in very young or immunosuppressed patients.
Results are obtained rapidly, however, and are not affected by prior BCG.
may be used after mantoux
Mantoux test
Mantoux test - usually offered to contacts of infected patients.
Positive in those who have had the BCG vaccine.
TB management
rifampicin, Isoniazid, pyrazinamide and ethambutol for 2 months,
then rifampicin and Isoniazid for a further 4 months.
Extended duration in TB meningitis, pericarditis, and spinal TB - meningitis 12 months + steroids
Rifamipicin s/e
Liver toxicity
Hepatic enzyme (p450) inducer
Turns bodily fluids red/orange colour.
Isoniazid s/e
Peripheral neuropathy (pyridoxine VB6 is given to prevent this)
hepatitis
agranulocytosis
liver enzyme inhibitor
Pyrazinamide s/e
hyperuricaemia causing gout
arthralgia, myalgia
hepatitis
Ethambutol s/e
Visual disturbance (colour blindness, loss of acuity etc.)
Avoid in chronic kidney disease - adjust dose
Main screening test for TB
Mantoux test
Which sputum sample needs 3 samples and is stained for acid fast bacilli
Sputum smear
(ziehl neilson stain)
the gold standard investigation for TB
more sensitive than a sputum smear and nucleic acid amplification tests
can assess drug sensitivities
can take 1-3 weeks (if using liquid media, longer if solid media)
sputum culture
TB test:
allows rapid diagnosis (within 24-48 hours)
more sensitive than smear but less sensitive than culture
Nucleic acid amplification tests (NAAT)
Latent TB treatment
3 months of isoniazid (with pyridoxine) and rifampicin OR 6 months of isoniazid (with pyridoxine)
