Additional Material Required

Sterile plating loops (10 µL), incubator at 37± 0.5oC,

biosafety hood with Bunsen burner, activated 2%

862 Concise Book of Medical Laboratory Technology: Methods and Interpretations

glutaraldehyde solution, vortex mixer, 0.1–0.5 mL

micropipettes, sterile micropipette tips.

Inoculum Preparation for Sensitivity Testing

a. Take a loopful aseptically from the Mycobacterium

tuberculosis colony grown on Lowenstein-Jensen slant.

b. Transfer it aseptically to the screw capped bottle

containing 0.1 mL of sterile distilled water and glass

beads, for inoculum preparation.

c. Close cap tightly and subject the contents of the bottle

to mechanical shaking (vortex) for 10 minutes.

d. Keep standing for 10 minutes before opening the

bottle.

e. Dilute this in saline to match McFarland 0.5 Standard.

This contains approximately 1.5 × 108

 org/mL.

f. Further dilute to 1: 10000 with saline. This is seed

culture. (10000–12000 org/mL).

g. Mix well and use this as inoculum.

h. Discard the container with glass beads in 2% activated

glutaraldehyde solution.

Test Procedure

1. Bring the primary/secondary drug containing

Lowenstein-Jensen media panel for MTB sensitivity

tests slants to room temperature.

2. Apply 100 µL from the seed stock to each slant of

primary/secondary drug containing LowensteinJensen media panel for MTB sensitivity tests also

control LJ.

3. A fresh disposable loop should be used for each slant.

4. Close the cap tightly and incubate at 37± 0.5° C.

5. Observe for the growth after 2 weeks till 8 weeks, every

week.

Interpretation of Results

As and when there is sufficient growth on control

(>100 colonies) compare the growth with the antibiotic

containing media.