TB Breath Test Proposal

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20.109 WF Pink Team Research Proposal

TB Breath Test

Project Overview: Developing a novel biosensor device to diagnose tuberculosis infection quickly and efficiently. Our aim is to create an engineered bacterial system to detect unique volatile organic compounds in the breath of those infected with TB and produce a visible output within minutes.


Disease background

  • Tuberculosis is an infectious (potentially fatal) disease caused by the bacteria Mycobacterium tuberculosis
  • 1/3 of world population is infected; in 2011 alone, 9 million new cases, and nearly 1.4 million TB-related deaths worldwide
  • TB usually affects the lungs, but can also affect brain, kidneys, spine
    • symptoms include coughing (blood), chest pain, weight loss, night sweats, fever, and chills
  • latent vs active infection
    • latent infection becomes active if immune system cannot repress bacteria's growth
    • 5-10% of latent cases will become active

2 widely used current tests:

  • Mantoux TB skin test injects a small amount of tuberculin into the skin
    • patient must return to clinic 48/72 hours later for evaluation of injection site
  • TB blood test (interferon-gamma release assay) measures immune system reaction to TB bacteria

Problem/Goals Statement:


  • current TB tests are invasive
  • commonly used TB skin test requires a follow-up visit 48 to 72 hours after tuberculin injection - an inconvenience to both patients and health care system
  • large need for administering TB tests given the prevalence of the disease
  • false positives can occur with current testing methods
  • we propose the creation of a better TB detection method that will address these shortcomings through biological engineering


  • to detect and concentrate a unique volatile organic compound (VOC) released from Mycobacterium tuberculosis in the breath of infected patients
  • to engineer a biological system that amplifies the VOC's signal, and quickly produces a visual output


  • has been identified that TB has a distinct scent
    • 4 volatile compounds from Mycobacterium tuberculosis and Mycobacterium bovis cultures grown in vitro that are distinctive volatile markers and detectable even before visible colony formation:
      • methyl phenylacetate
      • methyl p-anisate
      • methyl nicotinate
      • o-phenylanisole
  • VOCs can be detected in TB patient's breath

Predicted Outcomes: TBD!

  • Experiment 1: Can our biosensor uniquely identify at least one of the TB-indicative VOCs?
    • If yes, move on!
    • If no, look for alternative methods of capturing VOCs.
  • Experiment 2: Can our biosensor translate the VOC input to a visual output?
    • If yes, move on!
    • If no, consider changing input amplification inside the biosensor (perhaps in a positive feedback loop)
  • Experiment 3: Can our biosensor distinguish between healthy (negative control) and TB-infected individuals?
    • If yes, move on to future considerations!
    • If no, identify better target VOCs or detectors.


CDC: http://www.cdc.gov/tb/topic/basics/default.htm

  • Basic information about TB

Cambridge Pubic Health Department: http://www.cambridgepublichealth.org/services/diseases-conditions/TB-program/index.php

  • Test should be used on individuals with:
    • risk of exposure to active TB (e.g. health care workers)
    • immigration from TB prominent regions (Africa, Asian, Central and South America, Eastern Europe, the Caribbean, and the Middle East)
    • abnormal chest X-ray


  • Research that identified 4 unique VOCs in TB infections


  • Research that proved TB VOCs can be detected in patient breath