Sputum for AFB - osteosarcoma28

[ArchivalUser]

Can anybody please interpret the Sputum for AFB?
Kaplan[IM,pg 201,1st para,2nd line,2008-09] says AFB stain has limited sensitivity,and you need 3negative smears to reach >90%sensitivity?What this line means? and also,is it sufficient for only one sputum sample to be positive to say Sputum for AFB positive?

[ArchivalUser]

anybody........?

[ArchivalUser]

i think if 1 sample gives positive result = TB

but u cant rule out that person does not have TB if first sample is negative
we need to test 3 sputum samples and if none have AFB then only we say its not TB

[ArchivalUser]

thnks yazdoc..............

[ArchivalUser]

If 1 AFB smear out of 3 is positive, we still need to confirm by isolating M. tuberculosis in culture
If AFB is negative, then do bronchoscopy with BAL or tranbronchial lung biopsy and culture.
AFB smear can detect in the range of 5,000-10,000 bacilli/mL while culture can detect 50-100 bacilli/mL.