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 ...
Mycobacterium leprae is an intracellular, pleomorphic, non-sporing, non-motile, acid-fast, pathogenic bacterium. [3] It is an aerobic bacillus (rod-shaped bacterium) with parallel sides and round ends, surrounded by the characteristic waxy coating of mycolic acid unique to mycobacteria.
Other mycobacteria are also acid-fast. If the smear is positive, PCR or gene probe tests can distinguish M. tuberculosis from other mycobacteria. Even if sputum smear is negative, tuberculosis must be considered and is only excluded after negative cultures. [citation needed]
After the Ziehl-Neelsen staining procedure using carbol fuchsin, acid-fast bacteria are observable as vivid red or pink rods set against a blue or green background, depending on the specific counterstain used, such as methylene blue or malachite green, respectively. Non-acid-fast bacteria and other cellular structures will be colored by the ...
Gram-positive, nonmotile and acid-fast rods (1-3 μm x 0.2-0.4 μm). Sometimes long rods with occasional beaded or swollen cells having non-acid-fast ovoid bodies at one end. Colony characteristics. Smooth hemispheric colonies, usually off-white or cream colored. May be butyrous, waxy, multilobate and even rosette clustered (dilute inocula).
The genus is acid-fast to some degree, it stains only weakly Gram positive. The most common form of human nocardial disease is a slowly progressive pneumonia, the common symptoms of which include cough, dyspnea (shortness of breath), and fever. It is not uncommon for this infection to spread to the pleura or chest wall.
Other bacteria are commonly identified with a microscope by staining them with Gram stain. However, the mycolic acid in the cell wall of M. tuberculosis does not absorb the stain. Instead, acid-fast stains such as Ziehl–Neelsen stain, or fluorescent stains such as auramine are used. [4]
Mycobacteroides abscessus cells are Gram-positive, nonmotile, acid-fast rods about 1.0–2.5 μm long by 0.5 μm wide. They may form colonies on Löwenstein–Jensen medium that appear smooth or rough, white or greyish, and nonphotochromogenic. [citation needed]