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Oregon Health Authority

Lab Test Details

Mycobacterium - M. tuberculosis Complex Susceptibility Testing

Updated2/25/2025
Other Names Mycobacterium tuberculosis; MTBC
How to OrderOn 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 under test order.
AvailabilityAll Clients - Mycobacteriology labs
PerformedThursdays on regular business days
Time to ReportingMGIT 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

CollectionSubmit 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 (pdf).

Submitters should retain subcultures of all submissions as a backup precaution.
Optimal VolumeViable, Pure growth in/on media.

3 mL processed BTA material
Minimum VolumeViable, Pure growth in/on media.

2 mL processed BTA material
HandlingStore specimens at room temperatures (20-25°C) pending transport.
TransportPackage specimens to maintain room temperatures during transport.
Rejection CriteriaIsolates not identified as Mycobacterium tuberculosis complex Specimens are subject to the requirements of the OSPHL Specimen Submission Policy (pdf).
CommentsOriginal 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.

For each patient, TB susceptibility testing is performed once every three months 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

MethodologyMGIT PZA and IRE

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

Change Log

2/25/2025Detailed instructions for TB specimens attachment document updated
2/19/2025Updated How to Order; Availability; Rejection Criteria; Comments
4/24/2023Clarified Search Terms and How to Order; Edited Performed and Time to Reporting for MGIT PZA and IRE