AFB Isolate Susceptibility

Brief Description

Susceptibility testing is performed on Mycobacterium tuberculosis (MTB) isolates from new patients and every 3 months thereafter if cultures continue to be positive for MTB. Susceptibility testing is only performed on isolates of the Mycobacterium tuberculosis complex.   

Laboratory Unit



BD MGIT system

Specimen Collection

Pure culture Isolates:

Pure cultures submitted on solid media such as Middlebrook 7H10/7H11 or Lowenstein-Jensen slants. Cultures submitted in liquid 7H9 broth, MGIT, BacT/Alert MP bottles, VersaTREK bottles.


Cultures can be maintained at room temperature (15-30°C) during transit using a Category A shipping container.

Acceptable Specimen Type(s)

Pure culture isolates of Mycobacterium tuberculosis complex.

Test Request

Possible Results

  • Susceptible
  • Resistant
  • Excessive growth
  • Insufficient growth
  • Culture Contaminated

Reference Range


Unacceptable Conditions

  • Missing testing requisition
  • Missing minimum of 2 patient identifiers
  • Improper labeling
  • Improper storage/transport of specimen
  • No specimen received (empty collection tube).
  • Wrong specimen type

Interfering Substances


Result Reported

  • Isolates submitted for susceptibility testing only: 10-14 business days
  • Positive culture isolates from clinical specimens: 14-28  business days


Download this pdf file. Fee schedule

LOINC/Order Codes

29579-0 (Order code: 33950)