cobas® MTB

Qualitative nucleic acid test for use on the cobas® 6800/8800 Systems

A sensitive solution to a difficult diagnosis

Mycobacterium tuberculosis (TB, MTB) is a major global health problem, and is the leading cause of infectious disease deaths worldwide.1 This includes TB infections in people living with HIV/AIDS in which the infection is particularly lethal and difficult to detect.2 Early detection of TB is essential to further improve health outcomes for people with TB, and to reduce TB transmission more effectively. However, the delay in diagnosing TB and initiating appropriate medications is often long, especially in populations with poor access to health care.1 Tuberculosis is an airborne mycobacterial infection caused by the Mycobacterium tuberculosis complex (MTBC). MTBC is spread from one person to another through tiny droplets released into the air via coughs and sneezes. Resulting infection generally affects the lungs, but can also affect other parts of the body. Screening for active TB in selected risk groups is recommended by the WHO and CDC to improve early TB detection. More specifically, the CDC and WHO recommend performing a diagnostic nucleic acid amplification test from all patients suspected of having pulmonary TB.3,1 Additionally, WHO guidelines recommend all persons living with HIV/AIDS should be tested for MTB. cobas® MTB provides a sensitive solution to facilitate this difficult diagnosis, providing important information for patient care decisions.


Delivering exceptional assay performance

cobas® MTB includes a dual-target approach for detection of Mycobacterium tuberculosis. Selective amplification of target nucleic acid from the sample is achieved by the use of target-specific forward and reverse primers for the MTB complex which are selected from highly-conserved regions within the respective target organism. MTB is detected by two selective sets of primers and two probes targeting separated regions (dual-target – 16S rRNA gene and esx genes esxJ, esxK, esxM, esxP, and esxW).

cobas MTB assay performance
Speciem types
  • Raw Sputum
    Un-processed sputum. Sometimes used for direct AFB smear.

  • Sputum Sediment
    Sputum sediment from processed specimen. Typically used for routine testing including AFB smear, culture and PCR.

  • Bronchoalveolar lavage (BAL)
    Sediment BAL from processed specimen.


Demonstrated performance for improved patient care

This test is an automated, qualitative in vitro diagnostic test, that utilizes real-time polymerase chain reaction (PCR), for the direct detection of Mycobacterium tuberculosis complex DNA in either acid-fast bacilli (AFB) smear-positive or smear-negative, inactivated human respiratory specimens; including inactivated raw sputum, and inactivated digested and decontaminated (N-acetyl-L-cysteine/NaOH treated) sputum and bronchoalveolar lavage (BAL) samples

Key performance characteristics


Clinical Sensitivity and Specificity 

The performance of cobas® MTB using clinical samples was evaluated by testing prospective and archived specimens (raw sputum, sputum/BAL sediments) from persons with presumptive TB collected in Germany, South Africa, Switzerland, Uganda and Ukraine. Challenging culture positive, smear negative samples were detected with a sensitivity of 86.6% in raw sputum.

Sensitivity and specificity of cobas® MTB using clinical samples
      cobas® MTB
Sensitivity Raw Sputum C+/S 116/134
(79.6 - 91.8%)
C+/S+ 275/278
(96.9 - 99.7%)
C+/S± 391/412
(92.3 - 96.8%)
Sediment C+/S 116/148
(70.9 - 84.7%)
C+/S+ 287/289
(97.5 - 99.9%)
C+/S± 403/437
(89.3 - 94.5%)
Specificity Raw Sputum C-/S-
(95.7 - 99.1%))
Sediment C-/S-
(95.0 - 98.6%)

C = Culture, S = AFB smear

Package inserts

Access package inserts through your country’s Roche Diagnostics Website.



  1. WHO Global Tuberculosis Report, 2017 
  2. Cattamanchi A, Dowdy DW, Davis JL, Worodria W, Yoo S, Joloba M, et al. Sensitivity of direct versus concentrated sputum smear microscopy in HIV-infected patients suspected of having pulmonary tuberculosis. BMC Infect Dis. 2009; 9:53. 
  3. David M. Lewinsohn, Michael K. Leonard, Philip A. LoBue, David L. Cohn, Charles L. Daley, Ed Desmond, Joseph Keane, Deborah A. Lewinsohn, Ann M. Loeffler, Gerald H. Mazurek, Richard J. O’Brien, Madhukar Pai, Luca Richeldi, Max Salfinger, Thomas M. Shinnick, Timothy R. Sterling, David M. Warshauer, Gail L. Woods; Official American Thoracic Society/Infectious Diseases Society of America/Centers for Disease Control and Prevention Clinical Practice Guidelines: Diagnosis of Tuberculosis in Adults and Children, Clinical Infectious Diseases, Volume 64, Issue 2, 15 January 2017, Pages 111–115, (PDFs)

cobas® MTB Product Summary

  • Sample processing

    Manual liquefaction and inactivation followed by sonication and automated amplification and detection on the cobas® 6800/8800 Systems

  • PCR target region

    Dual-target – 16S rRNA gene and esx genes (esxJ, esxK, esxM, esxP, and esxW)

  • Internal control


  • Inclusivity for MTB complex

    M. tuberculosis, M. bovis, M. bovis (BCG), M. africanum, M. microti, M. canetti, M. orygis, M. caprae, M. pinnipedii, M. suricattae

  • Analytical specificity

    A panel of 178 bacteria, fungi and viruses, including those commonly found in respiratory tract, did not interfere with test performance

  • Analytical sensitivity Limit of Detection (LoD)

    8.8 CFU/mL (MTB; Raw sputum)

    7.6 CFU/mL (MTB; Sediment)

  • Interference (using endogenous potentially interfering substances)

    Not affected by the presence of elevated levels of gastric juice, hemoglobin, human whole blood, human DNA, mucin, pus and saliva

  • Exogenous interference

    Not affected by the presence of 48 drugs and OTC substances.

Ordering information
Product name P/N
cobas® MTB 08412197190
cobas®  MTB Positive Control Kit 07544812190
cobas®  6800/8800 Buffer Negative Control Kit 07002238190
cobas®  Microbial Inactivation Solution (MIS) 08185476001

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