mycobacterial infections (m tuberculosis) Flashcards
how does MTB spread
human to human
PROLONGED droplet exposure - talking, sneezing, coughing
who is at risk of getting TB
immunocompromised, malnourished, elderly
what does AFB smear positive mean
pt is highly infectious!
what does AFB smear negative, culture positive
less infectious!
what is the presentation of people with LBTI
asymptomatic and non infectious
what is quiescent infection
controlled, no signs and symptoms
what are the 2 tests for latent TB
- TST - tuberculin skin test
- IGRA - gamma interferon release assay - blood test
which form of TB is most common
post primary TB
what happens in post primary TB
occurs months-years after primary TB
due to reactivation of latent TB or reinfection
can occur in any organ of the body
s/s of active TB
fever, night sweats, weight loss, cough
haemoptysis
lymphadenopathy
crackles on auscultation
what test to do to confirm diagnosis of TB
microbiology testing!!!
early morning sputum - after settling of TB overnight, at least 2 samples
send samples of where u suspect the TB is at (eg tb meningitis - csf afb)
histology - presence of caseating granulomas and afb
how long does the culture of AFB take and what is the treatment till then
up to 8 weeks, so still treat with antibiotics!!!
what can replace the long culture period of AFB
PCR!
tells you if it is MTB and if they are MDR-TB!!!
what is the treatment for active TB
rifampicin
isoniazid
ethambutol
pyrazinamide
everyday orally for 6 months
how to tell if the patient is no longer infectious
2 weeks of taking all 4 drugs and 3 consecutive negative AFB smears
what is MDR-TB
drug resistance to at least 2 abx, the 2 most impt one
rifampicin and isoniazid
what is XDR-TB
extensively drug resistant TB
rifampicin, isoniazid, fluroquinolone n injectable drug
mostly seen in low SES country
how to prevent TB
BCG - derived from M bovis
should not be given to HIV infected individuals
** does NOT prevent infection!!! but prevent progression to disease and miliary TB in young children
