Acid fast stain

Acid-fast organisms will give a red colour whilst non acid-fast organisms will give a blue colour. 

Ziehl-Neelsen s carbol fuchsin may be prepared by dissolving 10 g of basic fuchsin in 100 ml of absolute ethanol and then adding this preparation to one litre of 5% phenol in water. 

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The same generally impervious properties make spores difficult to stain by simple stains. However, if a slide preparation of spores is warmed with a stain the spores are dyed so effectively that dilute acid will not wash out the colour. This is the basis of the acid-fast stain for spores. 

Tuberculous meningitis CSF culture, PCR evaluation (preferred), and acid-fast stain... 

Simplest method of diagnosis is detection of oocysts by modified acid-fast staining of a stool specimen. Standard ova and parasite test does not include Cryptosporidium. 

Tlie morphology of some bacteria, especially those that form spores, is distinctive enough under the light microscope to have value for identification. This means that differential staining techniques, such as the Gram stain or acid-fast stain, and fluorescence microscopy may help to determine the iden-... 

Acid-fast staining for Cryptosporidium sp. has recently become important because this parasite is now recognized as a cause of severe diarrhea in immunodeficient patients such as those with AIDS, and it can cause transient diarrhea in immunocompetent individuals. The modified acid-fast stain recommended is similar to that used to stain Nocardia spp. in that it uses milder acid decolorization. A variety of acid-fast and fluorochrome staining procedures have been described for Cryptosporidium spp., and all the procedures appear to work. 

Infected body materials must be sampled, if at all possible or practical, before the institution of antimicrobial therapy, for two reasons. First, a Gram stain of the material may reveal bacteria, or an acid-fast stain may detect mycobacteria or actinomycetes. Second, a delay in obtaining infected fluids or tissues until after therapy is started may result in falsenegative culture results or alterations in the cellular and chemical composition of infected fluids. 

Diagnosis of tuberculosis meningitis employs acid-fast staining, culture, and PCR of the CSF. 

The unusual features of the lipid constituents of M. tuberculosis were first observed by Aronson. The fat, as the lipids were at first termed, had acid-fast staining properties. Saponification of the fat yielded a quantity of soluble matter and a resistant residue. Aronson was able to prepare an acetate from the latter and identified the substance as an alcohol of very high molecular weight. The same author found that organic solvents removed some of the lipids with ease, these consisting largely of free fatty acids. 

Further investigation by Kresling confirmed earlier observations that saponification of the fat gave an alcohol of high molecular weight. He was unable to detect cholesterol in the tubercle lipids. It was found that ethereal hydrogen chloride would remove the acid-fast staining lipid fraction from the bacillary cell. 

The ether-soluble constituents of this purified wax, after saponification, contained fatty acids. The acid-fast staining property was ascribed to mycolic acid, a long-chain fatty acid. An alcohol, phthio-cerol, was also present and was obtained in crystalline form from ethyl acetate. In chloroform it had [a]o — 4.8°. The molecular formula corresponded to C35H720a or C86H74O3. The molecule contained two hydroxyl groups and one methoxy group, but the chemical constitution has not yet been settled. 

Tuberculosis can involve any region of the CNS and its coverings. The disease usually causes granulomatous inflammation with or without caseating necrosis, meningitis, or arteritis. The extensive time required to grow mycobacteria invites preliminary testing with IHC, PCR assay, or acid-fast stains. ... 

It is not necessary to carry out an acid fast stain (Chapter 4) on Gram-positive rods giving a positive spore stain, but this test should be carried out on Grampositive rods which cannot be demonstrated to contain spores. This stain is intended to differentiate the genus Mycobacterium and some Nocardia spp. on the basis of the lipid material present in the outer layers of the cell. 

Ziehl-Neelsen acid fast stain reveals alternate... 

Ziehl-Neelsen acid-fast stain A differential stain for organisms that are not decolorized by acid in alcohol, such as the bacteria that cause Hansen s disease (leprosy) and tuberculosis. 

Barden, H. Acid fast staining of oxidized neuromelanin and lipofuscin in the human brain. J. Neuropathol. Exp. Neurol. 1979, 38, 453 62. 

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