Preferred Sample Type
Suitable Specimen Types
- Sputum
- Trap
- Trap
10 mls (3 mls absolute minimum)
Turnaround Time
4 daysSample Stability
Samples stored at 4C;Mycobacterial detection (TB PCR)
General Information
The Xpert MTB/RIF test for use with the Cepheid GeneXpertR System is a PCR in-vitro diagnostic test for: 1) the detection of Mycobacterium tuberculosis complex DNA in sputum samples and 2) the detection of rifampin resistance associated mutations of the rpoB gene in samples from patients at risk for rifampin resistance. Culture remains the most sensitive test, particularly for smear negative samples. A negative test for direct detection by any method is not a rule out test.
Patient Preparation
For general aspects of taking respiratory samples we recommend that users follow either their local protocols or “The Royal Marsden Manual of Clinical Nursing Procedures”.
Sputum
Ask patient to take three deep breaths in through their nose, exhale through pursed lips and then force a deep cough.
Ask patient to expectorate into a 20ml white top sterile sample container.
Bronchoalveolar Lavage (BAL)
BAL should be collected according to local protocols using sterile fluids as the instillate. Recovered lavage fluid should be aseptically transferred to a 20ml white top sterile sample container
Nasopharyngeal wash: vacuum-assisted (trap) aspirate method
Nasopharyngeal wash should be collected according to local protocols using sterile fluids as the instillate.
Recovered mucus/fluid should sent in a 20ml white top sterile sample container or other well sealed sterile container.
Cerebrospinal fluid (CSF)
For CSF samples, the preferred volume is 10 mls but the minimum acceptable amount required for TB PCR is 3 mls. If less than 3mls is received the CSF will only be cultured for TB.
Notes
PLEASE NOTE: This test is only validated for respiratory samples, although other sample types will be tested if requested. Paraffin blocks can be tested (10x10µ sections are required). The test is not approriate for urine and blood samples.
Results are telephoned.
Please make sure sample forms and/or bags are labelled as biohazard.
For more information about TB testing services please see: NATIONAL MYCOBACTERIUM REFERENCE SERVICE (NMRS)
Specifications
- EQA Scheme?: Yes
- EQA Status: NEQAS