Ordering Guidance

This test does not provide rifampin resistance information and is most useful for non-sputum specimens. For sputum specimens, the recommended test is MTBXS / Mycobacterium tuberculosis complex, Molecular Detection and Rifampin Resistance, PCR, Sputum. MTBXS provides rapid resistance information to aid with patient management.

Additional Testing Requirements

This test must always be performed in conjunction with mycobacterial culture. If your facility is unable to perform mycobacterial culture, order CTB / Mycobacteria and Nocardia Culture, Varies concurrently with this test.

Shipping Instructions

Specimen must arrive within 7 days of collection; if greater than 7 days of collection, the specimen will be rejected.

Necessary Information

Specimen source is required.

Specimen Required

Submit a raw clinical sample (not a culture isolate) for testing.

Fresh, undigested specimens are preferred. If no fresh specimen is available, digested respiratory specimens treated with N-acetyl-L-cysteine/sodium hydroxide (NALC/NaOH) are acceptable for some specimen types. For detailed information, see the Specimen Type information below.

The high sensitivity of amplification by polymerase chain reaction (PCR) requires the specimen to be processed in an environment in which contamination of the specimen by Mycobacterium tuberculosis DNA is unlikely.

If a single specimen is being shared between mycobacteria culture, acid-fast smear, and/or M tuberculosis PCR, a minimum volume of 2 mL for body fluid, 3 mL for respiratory specimen, or a pea-sized piece of tissue should be obtained. Specimen volumes less than indicated may decrease sensitivity of testing. If insufficient volume is submitted, test or tests will be canceled.

Submit only 1 of the following specimens:

Preferred Specimen Types

Specimen Type: Body fluid

Sources: Body, bone marrow aspirate, ocular, or CSF

Container/Tube: Sterile container

Specimen Volume: 1 mL

Additional Information: Only fresh, non-NALC/NaOH-digested body fluids are acceptable.

Specimen Type: Gastric washing

Container/Tube: Sterile container

Specimen Volume: 2 mL

Collection Instructions: Neutralize specimen within 4 hours of collection with 20 mg of sodium carbonate per 2 mL of gastric washing.

Specimen Type: Respiratory

Sources: BAL, bronchial washing, tracheal secretion, or sputum

Container/Tube: Sterile container

Specimen Volume: 1 mL if only PCR ordered or 3 mL if PCR ordered with smear and culture

Additional Information: Before collecting sputum specimens, see Ordering Guidance. 

Specimen Type: Feces

Container/Tube: Sterile container

Specimen Volume: 5 to 10 g

Additional Information: Only fresh, non-NALC/NaOH-digested fecal specimens are acceptable.

Specimen Type: Tissue

Sources: Fresh tissue, bone, or bone marrow biopsy

Container/Tube: Sterile container

Specimen Volume: 5 to 10 mm

Collection Instructions: Keep moist with sterile water or sterile saline

Additional Information: Only fresh, non-NALC/NaOH-digested tissue is acceptable.

Specimen Type: Urine

Container/Tube: Sterile container

Specimen Volume: 1 mL

Collection Instructions: Collect a random urine specimen.

Acceptable Specimen Types

Specimen Type: NALC/NaOH-digested respiratory specimens

Sources: Lavage fluid, bronchial washing, gastric washing, respiratory fluid, sputum, or tracheal secretion

Container/Tube: Sterile container

Specimen Volume: 2 mL

Collection Instructions:

1. Submit digested specimen treated with NALC/NaOH.

2. Clearly indicate on container and order form that specimen is a digested specimen.