Mycobacterium tuberculosis complex Rapid Molecular Detection of Drug Resistance (Pyrosequencing)

Test Order Name - Mycobacterium tuberculosis Complex: Molecular Detection of Drug Resistance (Referred Testing to MDL-CDPH)

Synonym(s) - Pyrosequencing (PSQ) for the identification of mutations associated with drug resistance.

Methodology - Pyrosequencing (PSQ) is performed 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.

Acceptable Specimen Type(s) for Testing - Sediments or cultures.

Transport / Collection Medium - Sterile collection vial or liquid (MGIT) or solid (LJ Slant) culture.

Storage and Preservation of Specimen - Sediments: refrigerate at 4°C. Cultures: Incubated (35 to 37°C), prior to shipping at ambient temperature or cold pack.

Minimum Volume Required - 0.5 milliliters of sediment

Additional Collection Instructions - Fresh, pure growth of M.tb. is required for this test. Identification of M.tb. must be confirmed before testing.

Additional Required Information - Collection date and specimen source required. Indicate first line drug susceptibility results and patient history. Prior approval with the Microbial Diseases Laboratory (MDL) required.

Send Out? - Yes

Turnaround Time - 1 to 3 days

Testing Restrictions - None

Limitations / Notes / Disclaimers - There must be a satisfactory number of M.tb. bacilli to yield an acceptable result. Specimens with at least 0.5 milliliters and an acid-fast positive smear of 1+ or greater will most likely generate an acceptable result. Sometimes inhibitory substances in the specimen may prevent successful DNA amplification and pyrosequencing.