Stains & CD markers
Acid fast / Auramine-rhodamine

Last author update: 1 August 2015
Last staff update: 5 September 2023

Copyright: 2003-2024,, Inc.

PubMed Search: Acid fast

Nat Pernick, M.D.
Page views in 2023: 7,546
Page views in 2024 to date: 4,834
Cite this page: Pernick N. Acid fast / Auramine-rhodamine. website. Accessed July 13th, 2024.
Definition / general
  • Ziehl-Neelsen (classic): common method; bacteria stain bright red due to retention of carbol-fuchsin dye; background is methylene blue counterstain; procedure involves heat (#1, #2)
  • Ziehl-Neelsen (modified bleach): may be more sensitive than classic stain (Acta Cytol 2008;52:325,J Cytol 2012;29:165)
  • Ziehl-Neelsen (modified for stool specimens): does not require heating (Centers for Disease Control)
  • Kinyoun: common method; uses more concentrated fuchsin dye and lipid solvent, but no heat; bacteria stain bright red against green background (#1, #2)
  • Fite: to detect M. leprae (leprosy) and Rhodococcus (Diagn Cytopathol 2001;24:244); combines peanut / vegetable oil with xylene to minimize exposure of bacteria cell wall to organic solvents and protect precarious acid-fastness of organism (#1, #2)
  • Ellis and Zabrowarny: protocol excludes phenol; procedure (J Clin Pathol 1993;46:559)
  • Auramine-rhodamine: mixture of Auramine O and Rhodamine B dyes, auramine binds to mycolic acid in cell wall; detection requires a fluorescence microscope (mercury vapor lamp or LED), but is most sensitive stain for mycobacteria (Hum Pathol 1984;15:1085, PLoS One 2011;6:e22495); saves time in searching for microorganisms (Clin Infect Dis 2008;47:203); procedure
  • Water filters are recommended to reduce false positives due to non-TB mycobacteria (Appl Environ Microbiol 2007;73:6296)
Microscopic (histologic) images

Images hosted on other servers:


Oocysts: modified acid-fast stain

Stool specimen (Ziehl-Neelsen)

Oocysts: auramine-rhodamine stain


Acid-fast stain

Mycobacterium leprae:

Liver (Fite stain)

Mycobacterium tuberculosis:

Ziehl-Neelsen stains

Auramine stain of lung

Skin biopsies

Mycobacterium avium complex:

Site-unknown, breast and colon (Ziehl-Neelsen)


Fite-Faraco modified acid fast stain of lung


Tuberculous lymphadenopathy (Ziehl-Neelsen)

Pleural fluid


Acid fast stain

Back to top
Image 01 Image 02