Specimen Preparation

Proper decontamination and concentration of specimen

containing normal microbial flora are crucial to detection

of Mycobacterium tuberculosis. Specimen obtained from

sterile sites such as CSF, peritoneal or pleural fluids

do not need decontamination. However, since most

specimens for Acid Fast Bacilli smear and culture are from

respiratory tract and the mucous traps Acid Fast Bacilli

and protects other organisms from decontamination and

concentration, decontamination and liquefaction is a

must. Most satisfactory for this purpose is a combination

of N-acetyl-L cysteine (mucolytic agent) and 2% NaOH

(decontaminant). Petroffs method of decontamination

can also be used.

Test Procedure

For direct sputum screening use 10 µL of purulent

sputum or use 10 µL of decontaminated and concentrated

specimen.