Test Methodology

Incubation and automated growth detection using the BACTEC MGIT 960 system. Positive cultures will be tested using phenotypic and molecular (MALDI-TOF, Sanger sequencing) identification methods. See Mycobacterial Culture Identification test information.

Reflex Testing Criteria

If M. tuberculosis complex (MTBC) is isolated from a new patient, pyrosequencing and drug susceptibility testing will be performed and isolate will be forwarded for TB Genotyping.

Pre-Approval Required

Yes. Pre-approval needed before initial participation. This service is available to California public health laboratories only.

Supplemental Information and Required Form(s)

Form LAB 402 (PDF) “Mycobacteriology-Specimens for Isolation and Culture”

Instructions on completing this form.

Required Specimen/Sample Type(s)

BD Mycobacteria Growth Indicator Tube (MGIT) inoculated with processed decontaminated or sterile specimen material.

Minimum Volume Required

Not applicable

Specimen Stability

Rejection Criteria

Storage/Transport Conditions

MGIT culture should be shipped as soon as possible after inoculation. Tubes received more than 5 days after inoculation may be rejected. 

If MGIT cultures inoculated on Friday, incubate at 37˚C over the weekend and ship overnight on the following business day at ambient temperature.

Transport Medium, if applicable

Not applicable

Specimen Labeling

Two identifiers, including patient full name, and at least one other identifier (specimen accession number, date of birth, medical record number).

Shipping Instructions and Specimen Handling Requirements

Ship isolates at ambient temperature or with cold packs; do not freeze. 

Follow the appropriate DOT/IATA approved shipping procedures. 

All suspected or confirmed MTBC cultures should be shipped as a Category A Infectious Substance, Affecting Humans (UN2814). 

Ensure that culture isolates are sent in media flask or tubes containing a screw-top cap that is additionally sealed with parafilm or tape for additional protection against leaking.

Ship to:

Guidelines (PDF) for collection of sputum specimens for tuberculosis testing are available from APHL website (see Appendix A).

Turnaround Time

6 weeks for negative cultures

3 weeks if culture is positive for Mycobacterium tuberculosis complex (MTBC)

4 weeks for mycobacteria other than MTBC (non-tuberculous mycobacteria, NTMs)

Preliminary reports will be issued if the MGIT becomes positive and AFB are observed. 

Interferences & Limitations

MGIT cultures received with visible contamination may be rejected. 

Overgrowth of bacterial and/or fungal contaminants may interfere with the ability to isolate mycobacteria or other AFB.

Urine and blood specimens may interfere with growth detection of the MGIT culture. Contact MPDR Unit prior to submitting MGIT cultures inoculated with these specimen types.

Reference Range

Not applicable

Additional Information

MDL Point of Contact