Also found in: Thesaurus, Medical, Wikipedia.


Not decolorized by acid after staining, as bacteria that retain dye after an acid rinse.

ac′id-fast′ness n.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(Microbiology) (of bacteria and tissues) resistant to decolorization by mineral acids after staining
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014


resistant to decolorizing by acidified alcohol after staining.
ac′id-fast`ness, n.
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adj.1.acid-fast - not easily decolorized by acid solutions; pertains to micro-organisms (especially the tubercle bacillus that causes tuberculosis)
imperviable, impervious - not admitting of passage or capable of being affected; "a material impervious to water"; "someone impervious to argument"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
Mentioned in ?
References in periodicals archive ?
Slit-skin smear from the earlobe revealed numerous acid-fast bacilli with globi (Figure 3).
Necropsy and histologic investigation identified reduction in the diameter of the vertebral canal and spinal cord at cervical segments 8-9 with coalescing granulomas and intralesional acid-fast bacilli within the intertrabecular space, left side of the clavicular air sac, and cranial left lung.
Cytomorphology with acid-fast staining is a valuable diagnostic tool in cases of tuberculosis.
The bacterial tissue cultures, blood cultures, acid-fast bacilli smears and cultures on tissue failed to demonstrate any pathogenic organisms.
Tuberculosis is diagnosed on finding acid-fast bacilli (AFB) on direct microscopic examination of sputum smear but this is not a very sensitive technique2 and almost 50% cases with tuberculosis can present with negative results3,4.
A definitive preoperative diagnosis is frequently difficult to obtain since acid-fast bacilli smears or cultures, fine-needle aspiration and polymerase chain reaction (PCR) are often falsely negative.
The pus stained positive for bacteria and acid-fast bacilli, and culture was positive for Proteus vulgaris and mycobacteria.
We suggest 2 helpful although not so popular diagnostic methods--autofluorescence and acid-fast stain--for easy detection of CLCs.
Ziehl-Neelsen staining often fails to demonstrate acid-fast bacilli, and diagnosis rests on the detection of typical histological changes.
Peritoneal biopsy was negative for malignancy, acid-fast bacilli and Mycobacterium tuberculosis (MTB) complex DNA.
Background & objectives: Improper practices of making direct smears of sputum for detection of acid-fast bacilli (AFB) and of disposing sputum cups are hazardous.
The tissue sections were negative for acid-fast bacilli (AFB) by the Ehrlich-Ziehl-Neelsen stain, and cultures of the biopsy material and blood were negative.