Carbol fuchsin, carbol-fuchsin, carbolfuchsin, or Castellani's paint (
CAS
Cas may refer to:
* Caș, a type of cheese made in Romania
* ' (1886–) Czech magazine associated with Tomáš Garrigue Masaryk
* '' Čas'' (19 April 1945–February 1948), the official, daily newspaper of the Democratic Party of Slovakia
* ''CA ...
) is a mixture of
phenol and
basic fuchsin
Fuchsine (sometimes spelled fuchsin) or rosaniline hydrochloride is a magenta dye with chemical formula C20H19N3·HCl. that is used in
bacterial
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...
staining
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissues), in cytology (microscopic study of cells), and in the ...
procedures. It is commonly used in the staining of
mycobacteria because it has an affinity for the
mycolic acids found in their
cell membranes.
It is a component of
Ziehl–Neelsen stain, a
differential stain.
Carbol fuchsin is used as the primary stain dye to detect
acid-fast bacteria because it is more soluble in the cells' wall lipids than in the acid alcohol. If the bacteria is acid-fast the bacteria will retain the initial red color of the dye because they are able to resist the destaining by acid alcohol (0.4–1% HCl in 70% EtOH).
Additionally, it can be used for the staining of bacterial spores.
Carbol-fuchsin is also used as a topical
antiseptic
An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living tissue/skin to reduce the possibility of infection, sepsis, or putre ...
and
antifungal
An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as cryp ...
.
References
{{Stains
Microscopy
Microbiology techniques
Laboratory techniques
Histopathology
Histotechnology
Staining dyes
Staining
Phenols
Antiseptics
Disinfectants