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Lab Test Details

Mycobacterium - M. tuberculosis Complex Susceptibility Testing



Other Names Mycobacterium tuberculosis; MTBC
How to Order On the General Microbiology Test Request Form (OHA0060), in the “Mycobacteria” section, check the “AFBSUSC: M. tuberculosis complex susceptibility testing; isolate” box. Enter Date Culture Positive next to test order.

Private Care Laboratories

PerformedThursdays on regular business days.
Time to Reporting

MGIT PZA and IRE: Approximately 3 weeks from receipt of specimen.

Indirect Plate Method: Approximately 4 weeks after receipt of specimen.
CPT Code 

Specimen Collection Details


Submit TB culture isolates on Lowenstein-Jensen, 7H10, or other comparable solid AFB media. Failure to submit pure cultures may delay or adversely affect the testing process.

TB "Positive" liquid media tubes from MGIT systems will also be accepted for testing.

To submit specimens from BTA systems, do not submit in BacT bottle.
  • Remove 5 mL of material from the BacT bottle, spin for 15 minutes at 4150 rpm. Decant the supernatant, leaving approximately 0.5 mL. Resuspend and transfer to a microcentrifuge tube sealed with parafilm for submission.
  • Specimens that cannot be spun may be submitted in conical tubes sealed with parafilm if needed.
For more information about sending an aliquot of processed BTA material, see the OSPHL Detailed Instructions for TB Specimens.

Submitters should retain subcultures of all submissions as a backup precaution.
Optimal Volume

Viable, Pure growth in/on media.

3 mL processed BTA material

Minimum Volume

Viable, Pure growth in/on media.

2 mL processed BTA material


Store specimens at room temperatures (20-25°C) pending transport.


Package specimens to maintain room temperatures during transport.

Rejection CriteriaSpecimens are subject to the requirements of the OSPHL Specimen Submission Policy and Criteria, available at:
Comments Original material submitted for testing is retained for 6 months after receipt at the laboratory.

Submitters should retain subcultures of all submissions as a backup precaution.

TB susceptibility testing is performed at three-month intervals if M. tuberculosis continues to be isolated from the patient's specimens. Intervals are based on the dates of specimen collection.

For additional information or assistance, contact the laboratory at 503-693-4100

Method Details



Indirect Plate Method: Agar proportion includes Ofloxacin
Performance Specifications
Traditional agar proportion method used.

Change Log

Clarified Search Terms and How to Order; Edited Performed and Time to Reporting for MGIT PZA and IRE

Time to reporting: Removed reference to routine preliminary result reports
Methodology: Remove IRE for agar proportion testing

Comprehensive changes to detailed instructions attachment, review as new; Edit How to Order, Time to Reporting, Availability, Collection, and Methodology