Specimen Collection Guidelines

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Tuberculosis (TB) Specimens

Sputum Specimens for TB Testing


CARPHA performs a PCR assay using the Xpert MTB/RIF test (for use with the Cepheid GeneXpert® System). This is a semi-quantitative nested real-time PCR in-vitro diagnostic test for:

  1. the detection of Mycobacterium tuberculosis complex DNA in sputum samples or concentrated sediments prepared from induced or expectorated sputa that are either acid-fast bacilli (AFB) smear positive or negative; and
  2. the detection of rifampin resistance associated mutations of the rpoB gene in samples from patients at risk for rifampin resistance.
  3. The MTB/RIF test is intended for use with specimens from untreated patients for whom there is clinical suspicion of tuberculosis (TB). Use of Xpert MTB/RIF for detection of M. tuberculosis (MTB) or determination of rifampin susceptibility has not been validated for patients who are receiving treatment for tuberculosis.


Step Action
  • Select a sample container.
  • Instruct the patient to rinse his or her mouth with plain water twice before bringing up the sputum.
  • Open the lid of the sample container.
  • Have the patient inhale deeply 2-3 times.
  • Cough deeply from the chest, and then spit into the sputum container by bringing it closer to the mouth.
  • Care should be taken to avoid spoiling or soiling the soiling the outside of the container.
  • Secure the lid on the collection device.

Using a scissors to take the biopsy

  • Make sure the sputum sample is of good quality.
  • Check the sample for food particles, blood or substances that may inhibit PCR process.
  • The sample volume should be at least 1ml.


  • Treat all sputum samples as potentially infectious material and use leak proof containers for sample collection and transportation.
  • Specimens should be held at 2°C- 8°C (The sample remains viable at this temperature for 4-10 days.)
  • Transport the sample to CARPHA at (2°C- 8°C)