Test: | AFB Mycobacterium tuberculosis Amplified Direct Detection |
Synonym: | TBAPR, TB PCR, Qualitative Real Time PCR, TB NAAT and rifampin |
Method: | Cepheid GeneXpert MTB Assay to detect Mycobacterium tuberculosis (MTB) complex and rifampin directly from sputum only. |
Availability: | 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. |
Specimen: | 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. |
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. |
Volume: | 5-20 ml sputum |
Storage/Transport: | Prior to and during shipment: Refrigerated at 2-8 °C. Disinfect outside container and place each individual specimen in a sealed bag. |
Unacceptable: | 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. |
Reference Interval: | Negative |
Reportable Disease: | Presumptive positive MTB complex results are reported immediately to local or state health department. Refer to Nebraska DHHS Title 173, Communicable Diseases |
Comments: | 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 |