Cite this page: Pernick N. Acid fast / Auramine-rhodamine. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainsacidfast.html. Accessed January 17th, 2021.
Definition / general
- Acid fast refers to microorganisms whose cell wall has a high lipid content of mycolic acids and long chain fatty acids, which traditionally is considered to cause them to bind and retain the complex basic dye carbol-fuchsin even after strong decolorization with acid-alcohol (thus "acid-fast") (Wikipedia)
- Hänscheid et. al. believe auramine O actually binds to nucleic acids, not to the cell wall (see Lancet Infect Dis 2007;7:236, J Microbiol Methods 2008;74:119)
- Partially acid fast organisms exhibit both acid fast and non-acid fast bacilli and filaments in a single strain
- Standardization recommended for interpretation (Hum Pathol 2012;43:1845)
- Sputum smears may misidentify acid-fast bacilli as Mycobacterium tuberculosis in HIV+ patients (J Acquir Immune Defic Syndr 2013;63:168)
- Acid fast organisms include Mycobacteria, oocysts of Cryptosporidium parvum, Cyclospora, Isospora; also hooklets of cysticerci
- Partially acid fast organisms include Actinomyces: Dietzia (Int J Syst Evol Microbiol 2006;56:1667), Gordonia (Emerg Infect Dis 2000;6:382), Nocardiae (Surg Infect (Larchmt) 2012;13:163), Rhodococcus (South Med J 1991;84:1217), Tsukamurella (J Med Case Rep 2008;2:207); also rarely Mycobacterium peregrinum (J Clin Microbiol 2005;43:2015)
- Note: nucleic acid based tests can rapidly detect and speciate mycobacteria (Arch Pathol Lab Med 2008;132:1333, Thorax 2008;63:317)
Methods
Microscopic (histologic) images
Images hosted on other servers:
Cryptosporidium:
Cyclospora:
Isospora:
Mycobacterium tuberculosis:
Mycobacterium avium complex:
Mycobacterium leprae:
Nocardia:
Other:
Cyclospora:
Isospora:
Mycobacterium tuberculosis:
Mycobacterium avium complex:
Mycobacterium leprae:
Nocardia:
Other:
Videos
Acid fast stain