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Mycobacteriology: MTD test

Updated

12/13/2009

Other Names
Gen-Probe Amplified Mycobacterium tuberculosis Direct Test, NAAT for TB
How to Order
Under the Mycobacterium Section on the red General Microbiology Request Form  Hand Write “MTD”
Availability

Primary Samples: County and State Agencies

NALC-NaOH concentrated pellets: Private Care Laboratories
Methodology
Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test
Performed
Monday or Tuesdays and Thursdays
Time to Reporting
1 to 5 days
CPT Code
87556


Specimen Collection Details

Collection

Primary respiratory samples from County Health Departments are collected as per instructions at:

http://public.health.oregon.gov/LaboratoryServices/Documents/tb.pdf 

NALC-NaOH concentrated respiratory samples from Private Care Laboratories are submitted as per instructions at:

http://public.health.oregon.gov/LaboratoryServices/Documents/tb.pdf Page 4
Optimal Volume

Primary County respiratory samples:  1 – 5 ml

Private Care Lab concentrated pellets: 0.5ml – 1ml
Minimum Volume

Primary County respiratory samples:  1 ml

Private Care Lab concentrated pellets: 0.5ml
Handling
Keep specimen cold (2-8C) if transport is delayed
Transport

Primary samples: Delivery within 5 days of collection.

Private Care Lab concentrated pellets: Delivery within 3 days of concentration. Use appropriate shipping requirements.
Rejection Criteria
Unlabeled specimens, specimens not submitted per collection instructions, or without completed requisition forms will not be processed.
Comments

MTD is a Nucleic Acid Amplified Test (NAAT) that is FDA approved for respiratory samples from patients showing signs and symptoms consistent with active pulmonary tuberculosis (TB).  This test is not approved for patients who have taken medication for active TB disease in the past 12 months or for more than 7 days recently. The predictive value is related to the smear result and the prevalence of disease in a given population group. The MTD test does not distinguish between viable and non-viable organisms.

For diagnostic guidelines see:  https://public.health.oregon.gov/DiseasesConditions/CommunicableDisease/Tuberculosis/Pages/index.aspx