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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.
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Sputum acid-fast bacilli (AFB) microscopy services are established for every 100,000 population by the Revised National Tuberculosis Control Programme (RNTCP) (1).
(1) In a series of 19 patients at Groote Schuur Hospital over a 27-year period, (2) 1 patient was diagnosed ante mortem, 11 were found on autopsy to have nodular lesions, and 7 had miliary lesions; acid-fast bacilli were demonstrated in only 1!
An early morning sputum specimen was sent for TB assessment and all samples were negative for acid-fast bacilli. The initial sputum culture was positive for Streptococcus pneumoniae and he was treated appropriately.
To determine the sensitivity and specificity of the ELISpot test, the researchers recruited 347 patients suspected of having TB, but who were either unable to produce sputum, or who had had three consecutive negative acid-fast bacilli sputum culture results.
168 (80.0 %) samples showed the presence of acid-fast bacilli in the primary smear.
Polymerase chain reaction based detection of Mycobacterium tuberculosis in tissues showing inflammation without demonstrable acid-fast bacilli. Int.
Similarly Ziehl-Neelsen (ZN) staining of the histopathological tissue sections of MAP positive smear samples reflected the occurrence of acid-fast bacilli in 100% intestinal as well as lymph nodes samples.
Conjunctival biopsy revealed granulomatous epithelioid cell inflammation with small central necrosis without acid-fast bacilli. Extensive systemic examination, including bronchoscopy and transbronchial biopsy, provided the diagnosis
and negative for acid-fast bacilli. The organism was sensitive to cefotaxime, ceftriaxone and ciprofloxacin.
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.
The bacterial tissue cultures, blood cultures, acid-fast bacilli smears and cultures on tissue failed to demonstrate any pathogenic organisms.