Sorted By Test Name - Mayo Medical Laboratories

MTBPZ
56099
QTBG
83896
Interpretation: A positive result indicates the presence of Mycobacterium tuberculosis complex DNA.
Members of the Mycobacterium tuberculosis complex detected by this assay include Mycobacterium
tuberculosis, Mycobacterium bovis, Mycobacterium bovis Bacillus Calmette-Guerin, Mycobacterium
africanum, Mycobacterium canetti, and Mycobacterium microti. The other species within the
Mycobacterium tuberculosis complex (Mycobacterium bovis subspecies caprae and Mycobacterium
pinnepedi) should, in theory, be detected using the primer and probe sequences in this assay, but they
have not been tested at this time. This assay method does not distinguish between the species of the
Mycobacterium tuberculosis complex. A negative result indicates the absence of detectable
Mycobacterium tuberculosis complex DNA. Isoniazid (INH) resistance mediated through a katG mutation
will be reported when observed but lack of a katG mutation does not imply that the isolate is susceptible
to INH. There are other genetic loci in addition to katG that can contribute to resistance for this drug.
Reference Values:
Not applicable
Clinical References: 1. Iseman MD: A clinicianâ€s guide to tuberculosis. Philadelphia, PA.
Lippincott Williams & Wilkins, 2000 2. Centers for Disease Control and Prevention: Treatment of
Tuberculosis, American Thoracic Society, CDC, and Infectious Diseases Society of America. MMWR
Morb Mortal Weekly Rep 2003;52(No. RR-11):1-88
Mycobacterium tuberculosis Complex, Pyrazinamide
Resistance by pncA DNA Sequencing
Clinical Information: The protein product of the Mycobacterium tuberculosis complex pncA gene is
an enzyme that is responsible for activation of the prodrug pyrazinamide (PZA). DNA sequencing of the
Mycobacterium tuberculosis complex pncA gene can be used to detect mutations that correlate with in
vitro PZA resistance.(1,2) The sequencing result can be available in as little as 1 day after the
Mycobacterium tuberculosis complex isolate grows in culture, thereby providing a more rapid
susceptibility result than the average 10 to 14 days required by phenotypic broth methods.
Useful For: Detection of genotypic resistance to pyrazinamide by Mycobacterium tuberculosis
complex isolates
Interpretation: Polymorphisms in the pncA gene that have been previously correlated in our
laboratory with pyrazinamide (PZA) resistance will be reported as "Mutation was detected in pncA
suggesting resistance to pyrazinamide." Wild-type pncA or a silent pncA gene polymorphism (ie, no
change in the amino acid translation) will be reported as "No mutation was detected in pncA." New
polymorphisms in the pncA gene that have not previously been seen in our laboratory will require
additional testing using a reference broth method to determine their correlation with PZA resistance.
Reference Values:
Pyrazinamide resistance not detected
Clinical References: 1. Somoskovi A, Dormandy J, Parson LM, et al: Sequencing of the pncA Gene
in members of the Mycobacterium tuberculosis complex has important diagnostic applications:
identification of a species-specific pncA mutation in "Mycobacterium canettii" and the reliable and rapid
predictor of pyrazinamide resistance. J Clin Microbiol 2007;45:595-599 2. Dormandy J, Somoskovi A,
Kreiswirth BN, et al: Discrepant results between pyrazinamide susceptibility testing by the reference
BACTEC 460TB method and pncA DNA sequencing in patients infected with multi-drug resistant
W-Beijing Mycobacterium tuberculosis strains. Chest 2007;131:497-501 3. Somoskovi A, Parson LM,
Salfinger M: The molecular basis of resistance to isoniazid, rifampin, and pyrazinamide in
Mycobacterium tuberculosis. Respir Res 2001;2:164-168
Mycobacterium tuberculosis Infection Determination by
QuantiFERON-TB Gold, Blood
Clinical Information: Latent tuberculosis infection (LTBI) is a noncommunicable, asymptomatic
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