tuberculosis Flashcards
(21 cards)
tuberculosis causative organism
mycobacterium tuberculosis
primary tuberculosis
when a non-immune host is exposed to M.tuberculosis
small lung lesion called **Ghon focus ** develops + hilar lymph nodes = Ghon complex
normal people = lesion usually heals by fibrosis
immunocompromised = may develop disseminated disease (miliary Tb)
secondary (post-primary) TB
if host become immunocompromised, the initial infection may become reactivated.
reactivation generally occurs in apex of lung
sites of extrapulmonary infection in TB
CNS -> tuberculosis meningitis
vertebral bodies - Potts disease
cervical lymph nodes
renal
GI tract
tuberculosis pathophys
formation of granuloma - collection of epithelioid histiocytes
caseous necrosis in centre
type 4 sensitivity reaction
ghon complex = hilar ymph nodes + ghon focus
risk factors for TB
lived in Asia, latin america, eastern europe, africa
exposure to TB
HIV
immunocompromised - diabetics
silicosis
apical fibrosis
main method of screening for TB
1st = Mantoux test
interferon-gamma blood test
diagnosis TB
chest xray
sputum smear
sputum culture = gold standard ix
NAAT
TB chest xray
upper lobe cavitation = reactivated TB
bilateral lymph adenopathy
- unilateral = primary TB
TB sputum smear
3 specimens needed
stained for presence of acid-fast bacilli (Ziehl-Neelsen stain)
sensitivity is decreased in individuals with HIV
TB sputum culture
more sensitive than a sputum smear + NAATs
can assess drug sensitivities
(takes longer)
gold standard ix
TB nucleic acid amplification tests (NAAT)
allows rapid diagnosis (24-48hrs)
more sensitive than smear but less than culture
how are patients with latent tuberculosis diagnosed
having positive tuberculin skin test or Interferon-Gamma Release Assay (IGRA) combined with a normal chest xray (excluding active TB)
(patients asymptomatic + non-infectious)
management of latent tuberculosis
<35yrs if hepatotoxicity a concern = 3 months isoniazid (with pyridoxine) + rifampicin
HIV/had transplant = 6 months isoniazid (with pyridoxine)
is latent TB infectious
no ! no restriction in terms of emplyment
obvs changes if develops active form
management of active TB
first 2 months = RIPE
- rifampicin
- isoniazid
- pyrazinamide
- ethambutol
next 4 months = RI
- rifampicin
- isoniazid
meningeal TB = 12months + steroids
complications of TB treatment
immune reconstitution disease
- occurs 3-6wks after starting tx
- presents wit enlarging lymph nodes
drug side effects
rifampicin side effects
potent liver enzyme inducer
hepatitis, orange secretions
flu-like symptoms
isoniazid side effects, how is this managed
peripheral neuropathy - prevent with pyridoxine (Vit B6)
hepatitis, agranulocytosis
liver enzyme inducer
pyrazinamide side effects
hyperuricaemia –> gout
arthralgia, myalgia
hepatitis
ethambutol side effects
optic neuritis
- check visual acuity before + during tx
