Mycobacterium tuberculosis Nucleic Acid Amplification Testing (NAAT)

Brief Description

PCR testing is performed on new smear positive patients who have not had a positive NAAT or culture elsewhere and have been on treatment for less than 3 days. PCR testing may be performed on smear negative patients at the request of the submitter if TB disease is highly suspected.

Laboratory Unit



Cepheid GeneXpert- PCR

Specimen Collection


An early morning, deep cough in a sterile container.


Sputum (Sedimented and Raw) can be maintained at refrigerated temperature (2-8°C) during transit for no more than seven days after collection. 

Acceptable Specimen Type(s)

  • Sputum (Sedimented) – Minimum sample volume = 0.5 mL
  • Sputum (Raw) – Minumum sample volume = 1.0 mL

Test Request

Possible Results

  • Mycobacterium tuberculosis Not Detected
  • Mycobacterium tuberculosis Detected; Rifampin Resistance Not Detected
  • Mycobacterium tuberculosis Not Detected; Rifampin Resistance Detected
  • Unsatisfactory

Reference Range

  • MTB not detected
  • Rifampin Resistance not Detected

Unacceptable Conditions

  • Missing testing requisition
  • Missing minimum of 2 patient identifiers
  • Improper labeling
  • Improper storage/transport of specimen
  • No specimen received (empty collection tube).
  • Wrong specimen type
  • Specimen broken, damaged, or leaking upon arrival.

Interfering Substances


Result Reported

1 business day


Download this pdf file. Fee schedule

LOINC/Order Codes

17296-5 (Order code: 30800)