Does micrococcus reduce nitrate?

Micrococcus spp. are Gram-positive aerobic spherical cocci. They are catalase positive, reduce nitrate to nitrite and are usually non-motile.

What type of staining is negative staining?

Negative staining requires an acidic dye such as India Ink or Nigrosin. India Ink or Nigrosin is an acidic stain. This means that the stain readily gives up a hydrogen ion (proton) and the chromophore of the dye becomes negatively charged.

Is Micrococcus luteus oxidase positive or negative?

Micrococcus luteus They are positive for catalase and oxidase.

What color does gram-negative stain?

Gram-negative bacteria have walls with thin layers of peptidoglycan (10% of wall), and high lipid content. These stain pink.

What does micrococcus cause?

Micrococci have occasionally been reported as the cause of pneumonia, meningitis associated with ventricular shunts, septic arthritis, bacteremia, peritonitis, endophthalmitis, CR-BSI and endocarditis.

What type of chromophore is associated with a negative stain?

What type of chromophore is associated with negative stain? Negative stains have negatively charged chromophores and are repelled by negatively charged bacterial cells.

Could any stain be used for a negative stain?

What types of dyes are used for negative staining? Yes. Eosin and acid fuchsin can be used. BC acidic dyes have a negative charge that repel positive charged cell wall (from protons) by ionic repulsion, which allows for contrast of the cell’s surface.

Is Micrococcus coagulase negative?

Microbiology. Normal human skin flora includes coagulase-negative staphylococci, Corynebacterium spp., Micrococcus spp. and S. aureus for roughly 20–30% of all humans.

Is Micrococcus a pathogen?

Micrococcus luteus is considered a non-pathogenic saprophyte of human skin and eye. Disease in man caused by this organism is not recorded in medical literature.

Is Diplococci Gram negative?

Types. Examples of gram-negative diplococci are Neisseria spp. and Moraxella catarrhalis. Examples of gram-positive diplococci are Streptococcus pneumoniae and Enterococcus spp.

Which stain shows gram negative bacteria during staining?

Due to differences in the thickness of a peptidoglycan layer in the cell membrane between Gram positive and Gram negative bacteria, Gram positive bacteria (with a thicker peptidoglycan layer) retain crystal violet stain during the decolorization process, while Gram negative bacteria lose the crystal violet stain and …

Can a spirochete be a Gram negative bacteria?

While spirochetes are generally regarded as Gram negative bacteria, because they have a thin peptidoglycan, Gram staining is not commonly used to stain them. In the process of staining Borrelia burgdorferi, they have been shown to weakly stain Gram-negative. However, this is by default given that the secondary dye is used last.

How is the spiral morphology of a spirochete produced?

The spiral morphology of spirochetes ( Figure 37–1) is produced by a flexible, peptidoglycan cell wall around which several axial fibrils are wound. The cell wall and axial fibrils are completely covered by an outer bilayered membrane similar to the outer membrane of other Gram-negative bacteria.

Can a mycobacteria cell be stained with Gram stain?

Due to high amounts of lipids in their cell walls, mycobacteria cannot be stained with Gram stain and remain colorless. In the acid-fast staining procedure, mycobacteria are first stained with the red dye basic fuchsin and the cells are then decolorized and re-stained with methylene blue.

Can a spirochete be treated with an antibiotic?

Specialized “Darkfield Microscopy” or immunofluorescenct stains must be used instead. Spirochetes are rather susceptible to antibiotics and do not display much resistance. Successful antibiotic treatment of any spirochete may precipitate a Jarisch-Herxheimer Reaction.