Search results
Results from the WOW.Com Content Network
[1] [2] Once stained as part of a sample, these organisms can resist the acid and/or ethanol-based decolorization procedures common in many staining protocols, hence the name acid-fast. [ 2 ] The mechanisms of acid-fastness vary by species although the most well-known example is in the genus Mycobacterium , which includes the species ...
The results of Ziehl–Neelsen staining is variable because many fungal cell walls are not acid fast. [11] An example of a common type of acid-fast fungus that is usually stained with Ziehl–Neelsen staining is called Histoplasma (HP). [12] Histoplasma is found in soil and the feces of birds and bats. [13]
The Kinyoun method can be modified as a weak acid fast stain, which uses 0.5–1.0% sulfuric acid instead of hydrochloric acid.The weak acid fast stain, in addition to staining Mycobacteria, will also stain organisms that are not able to maintain the carbol fuchsin after decolorizing with HCl, such as Nocardia species and Cryptosporidium.
Sputum smears and cultures should be done for acid-fast bacilli if the patient is producing sputum. [1] The preferred method for this is fluorescence microscopy (auramine-rhodamine staining), which is more sensitive than conventional Ziehl–Neelsen staining. [4]
Acid-fast organisms display a reddish-yellow fluorescence. [2] Although the auramine–rhodamine stain is not as specific for acid-fast organisms (e.g. Mycobacterium tuberculosis or Nocardia ) as the Ziehl–Neelsen stain , it is more affordable and more sensitive, therefore it is often utilized as a screening tool.
[2] [3] 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). [4]
The two most common methods for visualizing these acid-fast bacilli as bright red against a blue background are the Ziehl-Neelsen stain and modified Kinyoun stain. Fite's stain is used to color M. leprae cells as pink against a blue background. Rapid Modified Auramine O Fluorescent staining has specific binding to slowly-growing mycobacteria ...
Mycobacterium tuberculosis group bacteria are 1.0-4.0 μm long by 0.2-0.3 μm wide in tissues. In culture, they may appear as cocci, or as bacilli up to 6-8 μm long. [citation needed] The bacteria stain Gram-positive, acid-fast. The cell wall contains as high as 60% lipid, giving the mycobacteria their hydrophobic characteristics, slow growth ...