Pre-Approval Required
Yes
Supplemental Information or Form
Form
LAB 444 (03/12) (MDL-N-25), EXAMINATION FOR MYCOBACTERIA TUBERCULOSIS DRUG
SUSCEPTIBILITY
Performed on Specimens From
Patients
suspected of having drug-resistant tuberculosis, patients who are especially
susceptible to treatment failure, cultures of M. tb complex mixed with
non-TB mycobacteria or other bacteria.
Acceptable Sample/Specimen Type for Testing
Sediment
or culture - At least 0.5 ml of a concentrated sample which is acid-fast smear
positive.
Minimum Volume Required
0.5
ml for sediment, more if preferred
Storage & Preservation of Sample/Specimen Prior to Shipping
If
sediment, refrigerate. If culture, incubate at 35-37°C.
Transport
None
Sample/Specimen Labeling
Patient’s
name, accession number
Shipping Instructions which Include Specimen Handling Requirements
Ship
cultures of M. tb complex as infectious substances. Sediments may be
shipped as diagnostic specimens with a cold pack.
Test Methodology
The
method used to identify mutations associated with drug resistance is
pyrosequencing (PSQ). The molecular targets in the first panel for detecting
isoniazid resistance are katG, inhA and ahpC
promoters and fabG1; that for rifampin is rpoB. The molecular
targets in the second panel for detecting resistance to quinolones is
gyrA and that for kanamycin, amikacin capreomycin and kanamycin is
rrs.
The
second panel is tested when any mutation is detected in the first panel, or
requested.
For
more information on pyrosequencing, see the bulletin “Pyrosequencing (PSQ) for XDR TB
Screening” (see Submission Instruction and Forms
page).
Turnaround Time
1 to 3
days
Interferences & Limitations
Inhibitory
substances in the specimen may prevent successful DNA amplification and
pyrosequencing.
Additional Information
None
MDL Points of Contact
Mycobacterial
Diseases Section (drug susceptibilities) (510) 412-3929
Email:
grace.lin@cdph.ca.gov