Test Methodology
Phenotypic drug susceptibility testing of
Mycobacterium tuberculosis complex (at critical concentration) by BACTEC MGIT 960 system.
Tested drugs: amikacin (AMK) 1.5 Āµg/ml, moxifloxacin (MFX) 0.25 Āµg/ml, capreomycin (CAP) 3 Āµg/ml, and ethionamide (ETA) 5 Āµg/ml. Susceptibility to moxifloxacin at 0.25 Ī¼g/ml predicts susceptibility to levofloxacin as well.
Reflex Testing Criteria
When resistant to moxifloxacin at 0.25 Āµg/ml, testing moxifloxacin MIC at 0.5, 1.0, 2.0, and 3.0 Ī¼g/ml is available upon request.
Pre-Approval Required
None
Supplemental Information or Form
Form LAB 444 (PDF)āMycobacteriology-Drug Susceptibility Testing of MTBC (CA only)ā
Instructions on completing the form.
Required Specimen/Sample Type(s)
Pure culture on solid or liquid media. Slants (LJ/ 7H10) or liquid cultures (MGIT broth) are preferable culture media for submission.
Minimum Volume Required
Viable growth should be present on subculture.
1 mL minimum if broth submitted.
Specimen Stability
Room Temp: up to 4 weeks
Refrigerated (2 ā 8Ā°C): up to 6 months; isolate may be subcultured
Frozen: Subculture prior to submission
Rejection Criteria
- Samples with insufficient or conflicting labelling
- Leaking samples
- Isolates with no growth
- Isolates that are nonviable
- Mixed cultures
- Specimen/sample types not meeting acceptance criteria
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.
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.
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 plate cultures.
Ship to:
California Department of Public Health
Microbial Diseases Laboratory
ATTN: TB Drug Susceptibility Testing Unit
850 Marina Bay Parkway, Specimen Receiving Room B106
Richmond, CA 94804
Specimen Collection Instructions, if applicable
Not applicable
Turnaround Time
Average 2 weeks
Interferences & Limitations
Results may be delayed or rejected if mixed culture is submitted.
Reference Range
Not applicable
Additional Information
Isolates will be forwarded to CDC if further characterization is needed.
MDL Point of Contact
For questions regarding submissions, please email
CDPHTBDST@cdph.ca.gov or call the MMPDS Section at (510) 412-3929