# Acid-Fast vs Non-Acid-Fast Bacteria – Key Differences

> Acid Fast bacteria resist the decolorizing by acid after staining. Non Acid Fast Bacteria readily resist the decolorizing by acid after staining.

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Author: Sourav Pan
Last updated: August 22, 2026

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## Comparison between Acid Fast and Non Acid Fast Bacteria

CharacteristicsAcid Fast bacteriaNon Acid Fast BacteriaResistance to decolonizationAcid Fast bacteria resist the decolorizing by acid after staining.Non Acid Fast Bacteria readily resist the decolorizing by acid after staining.Acid Staining colorAcid Fast bacteria appear in pink or red color.Non Acid Fast bacteria appear in blue color.StainIt retains the color of primary stain, carbol fuchsin.It retains the color of counterstain, methylene blue.Presence of Mycolic acidMycolic acid is present in cell wall.Mycolic acid is absent in cell wall.ExampleMycobacterium tuberculosis, Mycobacterium leprae,Mycobacterium avium-intracellulare complex, and Nocardia species.Escherichia coli is an example of acid fast bacteria.