Mycobacterium tuberculosis DNA Amplified Direct Detection
Supplemental Forms Required (only if not entered into NULirt) – 

Mycobacterium tuberculosis (MTB) Supplemental Form

NUlirt packing list or manual NPHL Test Order Form (completed in entirety) must accompany the specimen.


NAAT,  Quantitative Real Time PCR, Mycobacterium tuberculosis direct (MTB)


Cepheid GeneXpert MTB Assay to detect Mycobacterium tuberculosis (MTB) complex directly from sputum specimens. The test utilizes quantitative real time PCR technology that can be used on either acid fast bacilli (AFB) smear positive specimens or AFB smear negative specimens.


Monday-Friday, results same day if received in department by 0800 that day. STAT testing is not indicated and should not be performed.


Early morning sputum (expectorated or induced). Source of specimen is required. 
If for isolation release protocol, two sputum specimens may be tested per patient, but must be collected at least 8 hours apart.

  Collection Device:

Sterile leak-proof container. Place each individual specimen in a sealed bag.  Source of specimen indicated on requisition is required.
Specimen Labeling: Test subject to CLIA regulations and requires 2 patient identifiers on specimen container and requisition forms


Submit 5-15 mL sputum specimen in a sterile leak-proof container. Place each individual specimen in a sealed bag.


Prior to and during shipment: Refrigerated at 2-8 °C.

Shipping instructions, including specimen-handling requirements during transport:
All screw-top tubes must be sealed with parafilm or tape.  Vacutainer tubes do not require parafilm or tape to seal.
Package and ship as UN3373 Category B, Biological Substance. Place in biohazard bag with absorbent material. Transport by NPHL ground courier (NPHL brown shipper not required). If courier not available, contact Client Services (866) 290-1406 to arrange pickup.
See instructions and shipping address: http://nphl.org/


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

  Specimen Stability:

Refrigerate at 2-8 °C.

  Reference Interval:

A negative result does not exclude M. tuberculosis infection.

  Reportable Disease:

Positive results are reported to local or state health department and isolates sent to NPHL. Refer to Nebraska DHHS Title 173, Communicable Diseases.


The GeneXpert MTB/RIF Assay test is intended for use with sputum (induced or expectorated) specimens from patients showing signs and symptoms consistent with active pulmonary tuberculosis. GeneXpert® MTB/RIF Assay is to be used as an adjunctive test for evaluating either AFB smear positive or negative sediments prepared using NALC-NaOH digestion-decontamination.  Patients who are suspected of having pulmonary TB based on clinical evaluation and who have received NO anti-tuberculous therapy, less than 3 days of such therapy, or have not received such therapy in the last 12 months may be evaluated with this test.
MTD testing must be accompanied by an Acid Fast Bacilli Culture order. 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.

Pre-approval needed from state or local health department.  Send approval to NPHL@unmc.edu or call (402) 559-9444.

  Revised: 1/8/2020