Test Methodologyā
|
āPhenotypic drug susceptibility testing of Mycobacterium tuberculosis complex at critical concentrations by BACTEC MGIT 960 system.āā Routinely tested drugs: isoniazid (INH) 0.1 Ī¼g/ml, rifampin (RIF) 1 Āµg/ml, pyrazinamide (PZA) 100 Āµg/ml, and ethambutol (EMB) 5 Āµg/ml. Submitters may request the alternative first-line DST panel where moxifloxacin (MFX) 0.25 Āµg/ml is tested instead of EMB. āā
|
āReflex Testing
Criteria
|
āāāāIf resistance to any of the first-line drugs (āexcept PZA) is detected, second-line drug susceptibility testing will be performed.
The default second-line drug panel includes amikacin (AMK), capreomycin (CAP), kanamycin (KAN), rifabutin (RFB), ethionamide (ETA), and MFX. If MFX testing was previously performed as part of alternative first-line DST and resistance to RIF, INH, or MFX was observed, EMB will be included in the second-line DST panel.
In addition, if resistance to INH at 0.1 Ī¼g/ml is detected, susceptibility testing to INH at 0.4 Ī¼g/ml will be performed.
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.
|
āPre-Approval Requiredā
|
āāNo, unless:
Duplicate submission, i.e., samples from the same patient collected within 3 months from prior collection date.
|
Supplemental Information and Required Form(s)ā
|
Barcode submittal form 444 āMycobacteriology-Drug Susceptibility Testing of MTBC (CA only)ā or instructions for using the MDL Lab Web Portal (ETOR) can be found at: MDL Submission Instructions and Formsā.āā
āIndicate submitterās test results on the submittal form.āāā
|
āRequired Specimen Type(s)
|
āPure culture āon solid or liquid media.
Slants (LJ/ 7H10) or liquid cultures (MGIT broth) are the preferred culture media for submission.
|
āMinimum Volume Required
|
āViable growth should be present on subculture.
āā1.0 mL minimum if broth submitted
|
āSpecimen Stabilityā
|
āāāRoom 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
|
āRejection Criteria
|
- āāSamples with insufficient or conflicting labellingāā
- āLeaking samples
- āIsolates with no growth
- āIsolates that are nonviable
- Mixed cultures
- Specimen/sample types not meeting acceptance criteriaāā
|
āStorage/Transport Conditions
|
āGrow isolate under appropriate conditions and verify purity prior to shipping. Isolates may be stored refrigerated or at ambient temperature prior to shipping.ā
|
āTransport Medium,ā
if applicableāā
|
āNot Applicable
|
āSpecimen Labeling
|
āTwo identifiers, including patient full name, and at least one other identifier (specimen accession number, date of birth, medical record number).āā
|
āShipping Instructions and Specimen Handling Requirements
|
āāāShip 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 Healthā
Microbial Diseases Laboratory ā
ATTN: TB Drug Susceptibility Testing Unit āā
850 Marina Bay Parkway, Specimen Receiving Room B106
Richmond, CA 94804
|
āSpecimen Collection Instructions, if applicable
|
āāNot Applicable
|
āTurnaround Time
|
ā17 daysā
|
āInterferences & Limitations
|
āāResults may be delayed or unattainable if mixed culture is submitted.
|
āReference Range
|
āNot Applicableā
|
āAdditional Information
|
āāIsolates that are tested at MDL will be forwarded to the CDC if further characterization is needed or requested.
|
āMDL Point of Contact
|
āFor questions regarding submissions, please email
CDPHTBDST@cdph.ca.gov or call the MMPDS Section at (510) 412-3929āā
|