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Test Name

Mycobacterium tuberculosis Complex: Drug Susceptibility Testing, Second Line


Test ā€‹ā€‹ā€‹ā€‹ā€‹Mā€‹ā€‹ā€‹eā€‹thā€‹oā€‹ā€‹ā€‹ā€‹dā€‹ā€‹ā€‹ologā€‹yā€‹ā€‹ā€‹ā€‹


ā€‹Phenotypic drug susceptibility testing of Mycobacterium tuberculosis complex at critical concentrations by BACTEC MGIT 960 system.ā€‹ā€‹

ā€‹Tested drugs: amikacin (AMK) 1.5 Āµg/ml, capreomycin (CAP) 3 Āµg/ml, kanamycin (KAN) 3.5 Ī¼g/mL, rifabutin (RFB) 0.5 Ī¼g/mL, ethionamide (ETA) 5 Āµg/ml, and moxifloxacin (MFX) 0.25 Āµg/ml. If MFX testing was previously performed as part of alternative first-line DST, it will not be included in second line panel.

Susceptibility to MFX at 0.25 Ī¼g/ml predicts susceptibility to levofloxacin (LEV) as well; however, LEV can be tested instead of MFX upon request. MFX MIC may be requested by the submitter, but will only be performed after MFX resistance at 0.25 ug/mL is observed.

Second line DST for either streptomycin or ethambutol (if not included with first line panel) is available upon request only.

ā€‹Reflex Testing
Criteria

ā€‹When resistance to MFX at 0.25 Āµg/ml is detected, MFX MIC testing can be performed at 0.5, 1.0, 2.0, and 3.0 Ī¼g/ml upon request.

Molecular detection of drug resistance by pyrosequencing may also be performed on cultures including mixed or contaminated cultures when there is known or suspected phenotypic drug resistance.
ā€‹Pre-Aā€‹pproval Requiredā€‹
ā€‹ā€‹No, unless:
ā€‹Dā€‹uplicate submission, i.e., samples from the same patient collected within 3 months from prior collection date.

ā€‹Suppā€‹lemental Information and Required Form(s)ā€‹
Barcode submā€‹ittal form 444 ā€œMycobacteriology-Drug Susceptibility Testing of MTBC (CA only)ā€  or instructions for using the MDL Lab Web Portal (ETOR) can be found at:  MDL Suā€‹bmission Instructions and Formsā€‹.
ā€‹Indicate submitterā€™s test results on the submittal form.ā€‹ā€‹ā€‹
ā€‹Required Specimen Type(s)

ā€‹Pure culture ā€‹on solid or liquid media.
Slants (LJ/ 7H10) or liquid cultures (MGIT broth) are the preferred culture media for submission.

ā€‹Minimum Volume Required
ā€‹Viable growth should be present on subculture.
ā€‹ā€‹1.0 mL minimum if broth submitted

ā€‹Specimen Stabilityā€‹

ā€‹ā€‹Room Temp: up to 4 weeks.
Refrigerated (2 ā€“ 8Ā°C): up to 6 months.
Frozen: Subculture prior to submission.
If culture age exceeds above mentioned, subculture prior to submission and submit fresh culture.

ā€‹Rejection Criteria

  • ā€‹ā€‹Samples with insufficient or conflicting labellingā€‹ā€‹
  • ā€‹Leaking samples
  • ā€‹Isolates with no growth
  • ā€‹Isolates that are nonviable
  • Mixed cultures
  • Specimen/sample types not meeting acceptance criteriaā€‹ā€‹
ā€‹Storage/Transport Conditions

ā€‹Grow isolate under appropriate conditions and verify purity prior to shipping. Isolates may be stored refrigerated or at ambient temperature prior to shipping.ā€‹

ā€‹Transport Medium,ā€‹
if applicableā€‹ā€‹

ā€‹Not Applicable
ā€‹Specimen Labeling

ā€‹Two identifiers, including patient full name, and at least one other identifier (specimen accession number, date of birth, medical record number).ā€‹ā€‹
ā€‹Shipping Instructions and Specimen Handling Requirements

ā€‹ā€‹ā€‹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 Departā€‹ment of Public Healthā€‹
Microbial Diseases Laboratory ā€‹
ATTN:  TB Drug Susceptibility Testing Unit ā€‹ā€‹
850 Marina Bay Parkway, Specimen Receiving Room B106
Richmond, CA  94804

ā€‹Specimen Collection Instructions, if applicable

ā€‹ā€‹Not Applicable
ā€‹Turnaround Time


ā€‹17 daysā€‹
ā€‹Interferences & Limitations

ā€‹ā€‹Results may be delayed or unattainable if mixed culture is submitted.

ā€‹Reference Range
ā€‹Not Applicable
ā€‹Additional Information
ā€‹ā€‹The isolates will be forwarded to CDC if further characterization is needed. ā€‹

ā€‹MDL Point of Contact
ā€‹For questions regarding submissions, please email  CDPHTBDST@cdph.ca.gov or call the MMPDS Section at (510) 412-3929ā€‹ā€‹

ā€‹

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