MTD

AMPLIFIED MTD® (Mycobacterium Tuberculosis Direct) Test

Overview:
Although there has been a steady decline in tuberculosis due to significant public health efforts, TB is still a problem in the US. Also, since TB can become resistant to a drug or multiple drugs, it is important for the healthcare community to make the correct diagnosis quickly.

Gen-Probe's AMPLIFIED MTD Test detects Mycobacterium tuberculosis rRNA directly and rapidly while delivering the sensitivity of culture. The test is specific for Mycobacterium tuberculosis complex. Gen-Probe's test is the first FDA-approved direct test for helping to diagnose smear-positive and negative specimens. Recent CDC guidelines highlight the role of the Amplified MTD test in the diagnosis of a patient suspected of having TB.1

Use:
The MTD test is intended for use with specimens from patients that are showing signs and symptoms consistent with active pulmonary tuberculosis. The test is used in addition to acid fast bacillus (AFB) smear and culture. It is still important to perform culture due to the need for drug susceptibility information on isolates of Mycobacterium tuberculosis.

Features/Benefits:
  • Uses Gen-Probe's exclusive Transcription-Mediated Amplification (TMA)
  • TMA optimizes sensitivity by producing >1 billion copies of RNA amplicon
  • The amplicon is detected by the Hybridization Protection Assay (HPA)
  • Reduces operating costs by eliminating the need for expensive thermal cycling equipment
  • Decreases contamination by eliminating wash steps and the pipetting of amplicon
Solutions for the Laboratory:
The AMPLIFIED MTD test helps the lab improve workflow by utilizing a single tube format. It also increases efficiency by providing results in 2.5 to 3.5 hours offering diagnostic labs an effective tool in the fight against TB.

Solutions for Clinicians and the Healthcare System:
With pressure continuing to build to control healthcare costs, the Amplified MTD test helps hospitals and other healthcare institutions utilize resources more effectively. Specifically, the test helps make the correct diagnosis in the same day which is critical in the management of TB. Patients with Mycobacterium tuberculosis are quickly identified and the necessary treatment regimen can be initiated promptly.

By making the diagnosis quickly, the healthcare system is able to save the cost associated with inappropriate treatment and avoid the unnecessary isolation of patients with MOTT. The estimated costs associated with an inaccurate diagnosis of TB have been shown to be quite significant. For example, unnecessary institutional isolation due to an inaccurate positive diagnosis has been documented to have costs of $11,576.9

Table 1. MTD Laboratory Test Performance Using Patient Diagnosis as the Endpoint, Results from Smear-Positive Patients
  Sensitivity Specificity PPV NPV Number of Patients
MTD 96.9% 100% 100% 87.5% 39
BACTEC 96.9% 100% 100% 87.5% 39
LJ 87.5% 100% 100% 63.6% 39
7H10/7H11 96.7% 100% 100% 87.5% 37

Table 2. MTD Laboratory Test Performance Using Patient Diagnosis as the Endpoint, Results from Smear-Negative Patients
  Sensitivity Specificity PPV NPV Number of Patients
MTD 72% 99.3% 94.7% 95.3% 167
BACTEC 68% 100% 100% 94.7% 167
LJ 72% 100% 100% 95.1% 160
7H10/7H11 60% 100% 100% 93.4% 167


AMPLIFIED MTD (Mycobacterium Tuberculosis Direct) Test
Description: Direct target-amplified nucleic acid probe test for the in vitro diagnostic detection of Mycobacterium tuberculosis complex rRNA in acid-fast bacilli (AFB) smear positive and negative concentrated sediments from sputum, bronchial specimens, or tracheal aspirates. The Mycobacterium tuberculosis complex consists of M. tuberculosis, M. bovis, M. bovis BCG, M. africanum, M. canetti, and M. microti.
  PI / MSDS
50 Tests #301001


GEN-PROBE Detection Reagent Kit
Description: Detection reagent used on Leader luminometers for non-APTIMA Gen-Probe assays.
  PI / MSDS
1200 Tests #201791


References:
  1. Centers for Disease Control and Prevention. Update: Nucleic acid amplification tests for tuberculosis. 2000. MMWR 49:593-594.
  2. Wang, S.X. and L.Tay. 1999. Evaluation of three nucleic acid amplification methods for direct detection of Mycobacterium tuberculosis complex in respiratory specimens. J. Clin. Microbiol. 37:1932-1934.
  3. Bermann, J.S., G. Yuoh, G. Fish and G.L. Woods. 1999. Clinical evaluation of the enhanced Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test for rapid diagnosis of tuberculosis in prison inmates. J. Clin. Microbiol. 37:1419-1425.
  4. Chedore, P. and F.B. Jamieson. 1999. Routine use of the Gen-Probe MTD2 amplification test for detection of Mycobacterium tuberculosis in clinical specimens in a large public health mycobacteriology laboratory. Diagn. Microbiol. Infect. Dis. 35:185-191.
  5. Piersimoni, C., A. Callegaro, C. Scarparo, V. Penati, D. Nista, S. Bornigia, C. Lacchini, M. Scagnelli, G. Santini, and G. De Sio. 1998. Comparative evaluation of the new Gen-Probe Mycobacterium tuberculosis Direct Test and the semiautomated Abbott LCx Mycobacterium tuberculosis assay for direct detection of Mycobacterium tuberculosis complex in respiratory and extra pulmonary specimens. J. Clin. Microbiol. 36:3601-3604
  6. Gamboa, F., G. Fernandez, E. Padilla, J.M. Manterola, J. lonca, P. J. Cardona, L. Matas, and V. Ausina. 1998. Comparative Evaluation of initial and new versions of the Gen-Probe Amplified Mycobacterium Tuberculosis Direct Test for direct detection of Mycobacterium tuberculosis in respiratory and nonrespiratory specimens. J. Clin. Microbiol. 36:684-689.
  7. Della-Latta, P. and S. Whittier. 1998. Comprehensive evaluation of performance, laboratory application, and clinical usefulness of two direct amplification technologies for the detection of Mycobacterium tuberculosis complex. Am. J. Clin. Pathol. 110:301-310.
  8. Kaul, K et al. Direct sputum analysis for tuberculosis by polymerase chain reaction vs conventional techniques in a public hospital. In: Assessing Clinical Outcomes. American Association for Clinical Chemistry; 1994.
  9. Memish Z. Evaluation and follow up of infectious tuberculosis at the University of Ottawa. Can J Infect Dis. 1995:6:239-243.
  10. Behr, M.A., S.A. Warren, H. Salamon, P.C. Hopewell, A. Ponce de Leon, C.L. Daley, and P.M. Small. 1999. Transmission of Mycobacterium tuberculosis from patients smear-negative for acid-fast bacilli. Lancet. 353:444-449.
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