Acid-Fast Bacillus (AFB) Stain Only
Also known as: MS AFB
Use
This test is used primarily to monitor respiratory specimens in patients previously diagnosed with Mycobacterium tuberculosis. It should not be ordered without culture in previously undiagnosed patients due to its poor negative predictive value. An AFB stain allows for the rapid identification of acid-fast bacilli, which are characteristic of mycobacterial species, including Mycobacterium tuberculosis, and can aid in evaluating response to anti-tuberculosis therapy.
Special Instructions
The test is New York state approved and is appropriate only when following respiratory specimens on previously diagnosed patients. For comprehensive evaluation, it is recommended to use it in conjunction with culture tests to increase predictive value.
Limitations
The AFB stain alone has a poor negative predictive value in undiagnosed patients. It is crucial to confirm findings with culture, especially when evaluating new diagnoses. Non-respiratory specimens, swabs, and prepared slides are considered unacceptable for this test, limiting its use to respiratory specimens.
New York Approved
Methodology
Immunoassay (Auramine O Stain)
Biomarkers
LOINC Codes
- 72357-7
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Sputum
Volume
5-10 mL
Minimum Volume
1 mL
Container
Sterile container
Collection Instructions
Transfer 5-10 mL specimen to a sterile container. Place each specimen in an individually sealed bag. Specimen source required.
Causes for Rejection
Non-respiratory specimens. Swabs from any sites. Prepared slides.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 24 hours |
| Refrigerated | 1 week |
| Frozen | 2 weeks |