Collection of TB Samples

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 extrapulmonary as well as 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 rifampicin resistance associated mutations of the rpoB gene in samples from patients at risk for rifampicin resistance.

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 rifampicin susceptibility has not been validated for patients who are receiving treatment for tuberculosis.

STEP ACTION
1
  • Select a sample container.
2
  • Instruct the patient to rinse his or her mouth with plain water twice before bringing up the sputum.
3
  • Open the lid of the sample container.
4
  • 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.
5
  • 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.

Handling and Support

  • 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)

CARPHA HEAD OFFICE

  • 16-18 Jamaica Blvd,
    Federation Park,
    Port of Spain,
    Trinidad & Tobago
  • (+868) 299-0820
    (+868) 299-0895
    (+868) 622-4261
  • postmaster@carpha.org

CARPHA JAMAICA

  • Hope Gardens,
    Kingston 6,
    Jamaica
  • (+876) 977-3540
    (+876) 702-4235

CARPHA ST. LUCIA

  • P.O. Box 1111,
    The Morne, Castries,
    Saint Lucia
  • (+758) 452-2501
    (+758) 452-1087
  • (+758) 453-2721

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Copyright 2022 by The Caribbean Public Health Agency