Why is nocardia partially acid fast?

Some species are partially acid-fast (meaning a less concentrated solution of sulfuric or hydrochloric acid should be used during the staining procedure) due to the presence of intermediate-length mycolic acids in their cell wall.

Why is Nocardia and Mycobacterium acid-fast but Corynebacterium is not?

The chain length of these mycolic acids is longest in mycobacteria, intermediate in nocardia and shortest in corynebacteria. This explains why mycobacteria are generally acid fast; nocardia less acid fast; and corynebacteria are non-acid fast.

What makes an organism partially acid-fast?

The acid-fastness of Mycobacteria is due to the high mycolic acid content of their cell walls, which is responsible for the staining pattern of poor absorption followed by high retention. Some bacteria may also be partially acid-fast, such as Nocardia.

Does Nocardia have mycolic acid?

Members of the genus Nocardia are associated with the group of microorganisms known as the aerobic actinomycetes and belong specifically to the family Mycobacteriaceae. The nocardiae contain tuberculostearic acids but differ from the mycobacteria by possession of shorter-chained (40- to 60-carbon) mycolic acids.

How can you differentiate between Nocardia and Mycobacterium?

The laboratory diagnosis is based on microscopy and culture isolation, but Nocardia can be mistaken for Mycobacterium, as they not only grow in specific media for mycobacteria, but also form partially acid-fast beaded branching filaments, similar to those formed by rapidly growing mycobacteria¹⁸.

Nocardia Infection: Gram-positive, Partially Acid Fast, Aerobic, Filamentous Bacteria

Is Nocardia acid-fast?

Nocardia are weakly acid-fast following staining with the modified Ziehl-Neelsen or Kinyoun stain. Cultures may grow in a few days, but typically require 2 to 3 weeks of incubation.

How do the Mycobacterium and Nocardia react to acid fast stain?

Acidfast Stain: Background and Introduction. Mycobacterium and many Nocardia species are called acid-fast because during an acid-fast staining procedure they retain the primary dye carbol fuchsin despite decolorization with the powerful solvent acid-alcohol. Nearly all other genera of bacteria are nonacid-fast.

What is modified acid fast stain?

A modified acid-fast staining method was developed for rapid detection of Mycobacterium tuberculosis and its L forms, wherein carbol fuchsin and dioxogen were mixed into the sputum smear. With this method, the dyeing time is shortened and heating is not required.

What is meant by acid-fast bacilli?

Acid-fast bacillus (AFB) is a type of bacteria that causes tuberculosis and certain other infections. Tuberculosis, commonly known as TB, is a serious bacterial infection that mainly affects the lungs. It can also affect other parts of the body, including the brain, spine, and kidneys.

What are examples of acid-fast bacteria?

Why do acid-fast bacteria grow slowly?

Functions of the Acid-Fast Cell Wall Components

Layer 3: The mycolic acids and other glycolipids also impede the entry of chemicals causing the organisms to grow slowly and be more resistant to chemical agents and lysosomal components of phagocytes than most bacteria (Figure 2.3C. 2).

What is the principle behind acid-fast staining?

Principle of acid fast staining (in mycobacteria):

Heat softens the wax in the cell wall and allows the stain (basic fuchsin) to enter. The fuchsin dye is more soluble in phenol than in water or alcohol. Phenol in turn is more soluble in lipids or waxes, thus the dye-phenol mixture enters the cell.

What is the purpose of mycolic acid in the mycobacterial cell wall?

tuberculosis cell walls contain fatty molecules known as mycolic acids, which make the bacteria less susceptible to antibiotics. These molecules also help the bacteria to subvert and then hide from the immune system.

How is Actinomyces different from Nocardia?

The key difference between actinomyces and nocardia is that Actinomyces is a genus of actinobacteria comprised only of facultative anaerobic bacteria, while Nocardia is a genus of actinobacteria comprised only of strict aerobic bacteria. Actinomyces and Nocardia are two clinically important genera of actinobacteria.

Are Corynebacterium acid-fast?

Etiology. Corynebacterium spp., members of the family Corynebacteriaceae, are Gram-positive, non-spore- forming, non-motile, aerobic, pleomorphic rods with coccoid or club-shaped appearance that are catalase-positive and non-acid-fast (Boone et al., 2001; Greenwood, 2007).

What are examples of non-acid-fast bacteria?

What is the difference between acid-fast and non acid-fast bacteria?

The main difference between acid fast and non acid fast bacteria is that acid fast bacteria resist decolorizing by acid after accepting a stain whereas non acid fast bacteria are readily decolorized by acid after staining.

Why are acid-fast bacteria gram-positive?

Posted June 1, 2020. Acid-fast bacteria are gram-positive in terms of structure because they contain peptidoglycan in the cell wall. However, they stain poorly with Gram stain procedure, appearing weakly Gram-positive.

What is the significance of the presence of acid-fast bacteria in the sputum of a patient?

Sputum, or phlegm, is often used to test for Mycobacterium tuberculosis, to find out if a patient has TB. This bacterium is completely acid-fast, which means the entire cell holds onto the dye. A positive test result from the acid-fast stain confirms the patient has TB.

What parasites are acid-fast?

The oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria are each acid-fast.

Why does an acid-fast stain work on certain bacteria and not on others?

Acid-fast organisms are highly resistant to disinfectants and dry conditions. Because the cell wall is so resistant to most compounds, acid-fast organisms require a special staining technique.

How might the acid-fast characteristic of Mycobacterium?

How might the acid-fast characteristic of Mycobacterium enhance the organism's ability to cause disease? because they have a waxy coating around their cell that prevents alot of different things from getting into the cell. Including antibiotics if a person is sick. making the chances of disease more likely.

How do mycobacteria appear on acid-fast staining?

Principle of Acid-Fast Stain

When the smear is stained with carbol fuchsin, it solubilizes the lipoidal material present in the Mycobacterial cell wall but by the application of heat, carbol fuchsin further penetrates through lipoidal wall and enters into cytoplasm. Then after all cell appears red.

Why do acid-fast bacteria retain the carbol fuchsin?

The primary stain used in acid-fast staining, carbol fuchsin, is lipid-soluble and contains phenol, which helps the stain penetrate the cell wall. This is further assisted by the addition of heat in the form of heat (steam).

Is Nocardia aerobic or anaerobic?

Another useful clue is that Nocardia grow under aerobic conditions, whereas Actinomyces grow under anaerobic conditions.