Sputum

Collect 5 to 10 mL in a sterile container from an early

morning specimen of deep productive cough. For induced

specimen use sterile saline, have patients rinse mouth

with water to minimize specimen contamination with

food particles, mouthwash, or oral drugs.

Urine

As organisms accumulate in the bladder overnight, first

morning void provides best yield. Collect midstream clean

catch urine, first morning catheterization/suprapubic taps

in sterile containers.

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 AFB smear and culture are from respiratory tract and

the mucous traps AFB 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.

Preparation of Kirchner Medium

1. Reconstitute the Kirchner selective enrichment with

1 mL of sterile distilled water provided with the kit.

2. Transfer reconstituted selective enrichment aseptically

to the Kirchner medium base, which is now ready to

use as ‘Kirchner Medium’.