Troubleshooting

Problem: Growth on the slant within first week of incubation

Possible causes Solutions

1. Improper decontamination of sputum Proper decontamination and concentration of specimen containing normal microbial flora

specimen due to which contaminants are crucial to detection of Mycobacterium tuberculosis. Therefore, proper decontamination

over grow of sputum specimen should be carried out using Lyfectol

2. Fast growing organism of Mycobacterium Confirm the type of organism grown with biochemical tests

species

Problem: Collapse of slants

Possible causes Solutions

1. Improper transportation, i.e. kits Discard the collapsed slant and use fresh slant for testing

subjected to violent jerks and vibrations

or not handled with care during storage,

shipping and incubation

2. Contaminated slants If the slants are found contaminated because of various reasons, discard the slants and use

fresh slants to perform the test

3. Contaminated untreated sputum sample used Pretreat sputum sample prior to inoculation

Susceptibility Testing of

Mycobacterium tuberculosis

Resistance to antitubercular agents was recognized soon

after their introduction in early 1960s, and standardized

methods for antimicrobial susceptibility have been

developed. Routine laboratory susceptibility testing of

primary TB isolates has not been generally suggested

unless drug resistance in a particular community exceeds

5%. However, with the resurgence of TB drug resistance,

CDC USA has recently recommended that susceptibility

tests should be performed on all primary isolates.