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 Test Order

Mycobacterium tuberculosis complex:
Molecular Detection of Drug Resistance

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 sample  which is acid-fast smear positive is requested.

Minimum Volume Required

0.5 ml for sediment

Storage & Preservation of Specimen Prior to Shipping

If sediment, refrigerate. If culture, incubate at 35-37°C.

Transport Medium

None

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

Pyrosequencing (PSQ) to identify mutations associated with drug resistance in the following genes: rpoB for rifampin, katG, inhA promoter, and ahpC for isoniazid, gyrA for fluoroquinolones, and rrs for injectable drugs such as amikacin, capreomycin, or kanamycin.  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

There must be a satisfactory number of TB bacilli to yield an acceptable result.  Specimens with at least 0.5 ml and an acid-fast positive smear 1+ or greater will generally generate an acceptable result.  Sometimes inhibitory substances in the specimen may prevent successful DNA amplification and pyrosequencing.

Additional Information

None

Mycobacteriology (drug susceptibilities) Contact

(510) 412-3929

 

 
 
Last modified on: 8/20/2013 2:29 PM