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microbial diseases laboratory

Test Name 

Mycobacterial Culture Identification

Test Methodology

Mycobacterial cultures will be tested using phenotypic and molecular testing methods: Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) mass spectrometry and partial 16S rRNA and cpn60 gene DNA sequencing.

Reflex Testing Criteria

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

Pre-Approval Required

None, unless from source other than human.

Supplemental Information and Required Form(s)

Form LAB 443 (PDF) “Mycobacteriology-Culture Identification”

Instructions on completing this form.

Required Specimen/Sample Type(s)

Pure isolates from human specimens on solid culture or in liquid media; other sample types (animal, environmental) only if pre-approved. Slants (LJ/ 7H10) are preferable culture media. Liquid cultures are also acceptable.

Minimum Volume Required

Viable growth should be present on subculture.

Specimen Stability

Room Temp: up to 4 weeks
Refrigerated (2 – 8°C): up to 6 months; isolate may be subcultured 
Frozen: Subculture prior to submission

Rejection Criteria

  • Submissions with insufficient or conflicting labelling
  • Leaking samples
  • Samples with insufficient quantities
  • Samples that are too old or non-viable
  • Specimen/sample types not meeting acceptance criteria, if no prior approval was received
  • Mixed cultures may be rejected

Storage/Transport Conditions

Grow isolate under appropriate conditions and verify purity prior to shipping.  Isolates may be stored under refrigeration or ambient temperature prior to shipping.

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. DO NOT send a plate culture.

Ship to:

California Department of Public Health
Microbial Diseases Laboratory
ATTN: Mycobacterial & Parasitic Diseases Ref. Unit 
850 Marina Bay Parkway, Specimen Receiving Room B106
Richmond, CA 94804

Specimen Collection Instructions, if applicable

Not applicable

Turnaround Time

4 weeks

Interferences & Limitations

Unable to identify if submitted culture is overgrown by bacterial and/or fungal contaminants or if the culture is non-viable.

Reference Range

Not applicable

Additional Information

The isolates will be forwarded to CDC if further identification is needed, or upon request.

MDL Point of Contact

For questions regarding submissions, please email or call the MMPDS Section at (510) 412-3924.

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