for acid-fastness particularly useful in diagnosis. The following are notable examples of structures which are acid-fast or modified acid-fast: All mycobacteria – M. tuberculosis, M. leprae, M. smegmatis and atypical Mycobacterium Actinomycetes (especially some aerobic ones) with mycolic acid in their cell wall (note Streptomyces do NOT have); not to be confused with Actinomyces, which is a non-acid-fast genus of actinomycete Nocardia (weakly acid-fast; resists decolorization with weaker acid concentrations) Rhodococcus Gordonia (an actinomycete) Tsukamurella Dietzia Head of sperm Bacterial spores, see Endospore Legionella micdadei Certain cellular inclusions e.g. Cytoplasmic inclusion bodies seen in Neurons in layer 5 of cerebral cortex neuronal ceroid lipofuscinosis (Batten disease). Nuclear inclusion bodies seen in Lead poisoning Bismuth poisoning. Oocysts of some coccidian parasites in faecal matter, such as: Cryptosporidium parvum, Isospora belli Cyclospora cayetanensis. A few other parasites: Sarcocystis Taenia saginata eggs stain well but Taenia solium eggs don't (can be used to distinguish) Hydatid cysts, especially their "hooklets" stain irregularly with ZN stain but emanate bright red fluorescence under green light, and can aid detection in moderately heavy backgrounds or with scarce hooklets. Fungal yeast forms are inconsistently stained with Acid-fast stain which is considered a narrow spectrum stain for fungi. In a study on acid-fastness of fungi, 60% of blastomyces and 47% of histoplasma showed positive cytoplasmic staining of the yeast-like cells, and Cryptococcus or candida did not stain, and very rare staining was seen in Coccidioides endospores. References Online protocol examples Ziehl–Neelsen protocol (PDF format). Alternate Ellis & Zabrowarny method for staining AFB. Bacteria Staining