AFB Mycobacterium tuberculosis Amplified Direct Detection
Order in NUlirt or complete NPHL Test Order Form with
Supplemental Forms RequiredMycobacterium tuberculosis (MTB) Supplemental


TBAPR, TB PCR, Qualitative Real Time PCR, TB NAAT and rifampin


Cepheid GeneXpert MTB Assay to detect Mycobacterium tuberculosis (MTB) complex and rifampin directly from sputum only.


Monday - Friday by 0800. STAT testing is not indicated and should not be performed. If for isolation release protocol, two sputum specimens may be tested per patient, but must be collected at least 8 hours apart.


Early morning Sputum (expectorated or induced). Source of specimen indicated on requisition is required. MTB testing must be accompanied by an Acid Fast Bacilli Culture order (AFBCU). Routinely, only one specimen per patient will be tested (If for isolation release protocol, 2 specimens may be tested, but must be at least 8 hours apart.) Positive AFB smears on first time AFB positive patients will be automatically reflexed for testing.
NOTE: Document on test request form if sputum from a Cystic Fibrosis patient.
NOTE: Intended use for patients who are suspected of having pulmonary TB based on clinical evaluation and who have received NO anti-tuberculous therapy, or less than 3 days of such therapy.

  Collection Device:

Sputum in a sterile leak-proof container. Sputum samples are the only FDA approved source for use with Cepheid GeneXpert MTB Assay. Store and transport refrigerated at 2-8°C.
Specimen Labeling: Test subject to CLIA regulations and required 2 patient identifiers on specimen container and requisition forms


5-20 ml sputum


Prior to and during shipment:  Refrigerated at 2-8 °C. Disinfect outside container and place each individual specimen in a sealed bag. 

Shipping instructions, including specimen-handling requirements during transport:  Seal screw-top tubes with Parafilm™ or tape and place in biohazard bag with absorbent material.

Place specimen inside leak proof secondary container (biohazard bag and if transporting by air, use Tyvek™ Envelope) with adsorbent material. The secondary container must be packed inside an approved Category B shipping container filled with frozen gel-packs to keep specimen refrigerated. Position NUlirt packing list or NPHL Test Order form between secondary container and box lid. Seal with tape.  Label outer box as UN3373 Category B, Biological Substance. Transport by NPHL ground courier. If courier not available, ship by FedEx, UPS, or USPS (1st Class, Priority or Express Mail). Follow appropriate DOT/IATA Regulation Guidelines.  For assistance, call NPHL State Training Coordinator at (402) 559-3590.  
See instructions and shipping address: http://nphl.org/

NUlirt packing list or appropriate paperwork (completed in entirety) must accompany specimens.


Bloody specimens, leaking containers, Non-sputum specimen. Swabs.  Specimens with food or solid particles.

  Specimen Stability:

Refrigerate 2-8°C up to 7 days. Samples should be held at 2–8 °C prior to processing whenever possible. However, if necessary, the samples can be stored at 35 °C for a maximum of 3 days and at 2- 8 °C for an additional 7 days. 
Processed sputum specimen sediments may be stored at 2° to 8°C for up to 7 days prior to testing.

  Reference Interval:

A negative result does not exclude M. tuberculosis complex infection.

  Reportable Disease:

Presumptive positive MTB complex results are reported immediately to local or state health department. Refer to Nebraska DHHS Title 173, Communicable Diseases


This test utilizes quantitative real time PCR technology that can be used on either acid-fast bacilli (AFB) smear positive sputum specimens or AFB smear negative sputum specimens. Based on CDC recommendations, the test is appropriate for patients showing symptoms of active pulmonary tuberculosis and for whom the test result would alter case management or TB control activities. A specimen with a first time AFB positive smear on a suspect tuberculosis patient will also be automatically reflexed for Mycobacterium TB Amplified Direct Testing. Only one specimen per patient will be tested

  Revised: 6/11/2021