Test Procedure

Kirchner Medium

1. Bring the Kirchner medium to room temperature.

2. Label the Kirchner medium appropriately.

3. Draw 10 µL of the decontaminated and concentrated

specimen from the reconstituted pellet with a sterile

calibrated loop.

4. Inoculate in Kirchner medium aseptically.

5. Close the Kirchner medium cap tightly and incubate at

37 ± 0.5° C.

6. Observe for growth every third day till 8 weeks.

Lowenstein-Jensen Slant

1. Bring the Lowenstein-Jensen medium slant to room

temperature.

2. Label the Lowenstein-Jensen medium slant

appropriately.

3. Draw 10 µL of the decontaminated and concentrated

specimen from the reconstituted pellet with a sterile

calibrated loop and plate it on the Lowenstein-Jensen

medium slant aseptically.

4. For quantitative evaluation prepare bacterial

suspension to match McFari land 0.5 standard, dilute

this 1:10000 and Seed 100 µL on the LowensteinJensen medium slant aseptically (seed stock consists

of approximately-15000 organisms/mL).

5. Close the Lowenstein-Jensen slant cap tightly and

incubate at 37± 0.5oC.

6. Observe for growth weekly till 8 weeks.

Interpretation of Results

a. Mycobacterium tuberculosis colonies on LowensteinJensen slant may be detected from third week onwards

up to 8 weeks. The colonies are characterized by rough

granular buff colored growth, which has initial size of

1–3 mm and full-grown size of 5–8 mm.

b. Mycobacterium tuberculosis growth in Kirchner

medium is characterized by fluffy growth to small

granules. The granules sediment to the bottom.

c. Since both the media differ in their composition,

growth of Mycobacterium tuberculosis in either

medium should be considered as a positive culture

result. The growth needs to be identified.

Remarks