AFB
Medical abbreviation · Laboratory Test
| Stands for | Acid-fast bacilli |
|---|---|
| Categories | Medical |
AFB stands for Acid-fast bacilli, a laboratory test abbreviation.
Mycobacteria such as Mycobacterium tuberculosis, which resist decolorization by acid-alcohol after staining, and the smear and culture tests that look for them. Tuberculosis evaluation typically requires three sputum specimens collected 8 to 24 hours apart, at least one early-morning sample.
Example: AFB smear 2+; patient remains in airborne isolation pending TB NAAT.
Usage notes
The waxy, mycolic acid-rich cell wall is what makes the organisms acid-fast. Classic stains are Ziehl-Neelsen and the fluorescent auramine-rhodamine method. Mycobacterial cultures can take up to six to eight weeks, so molecular tests are now used to confirm TB and detect rifampin resistance quickly. Nocardia is weakly acid-fast.
Related abbreviations
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- ABG – Arterial blood gas
- ABO – ABO blood group system
- ACT – Activated clotting time
- AG – Anion gap
- Alb – Albumin
- ALC – Absolute lymphocyte count
- ALP – Alkaline phosphatase
- ALT – Alanine aminotransferase
- ANA – Antinuclear antibody
- ANC – Absolute neutrophil count
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This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.