What part of the bacterial cell is stained by the Gram stain?

What part of the bacterial cell is stained by the Gram stain?

Gram-positive bacteria have cell walls that contain thick layers of peptidoglycan (90% of cell wall). These stain purple. Gram-negative bacteria have walls with thin layers of peptidoglycan (10% of wall), and high lipid content. These stain pink.

Why is Gram staining used?

A Gram stain is most often used to find out if you have a bacterial infection. If you do, the test will show if your infection is Gram-positive or Gram-negative.

Is Gram positive bacteria antibiotic resistant?

The most important gram-positive resistant organisms include penicillin-resistant Streptococcus pneumoniae, methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci, methicillin-resistant Staphylococcus aureus with intermediate resistance to vancomycin, and enterococcal strains that express high …

What antibiotics work against Gram positive bacteria?

Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms.

How does Gram positive bacteria respond to antibiotics?

In contrast, the thick, porous peptidoglycan layer in the cell wall of Gram-positive bacteria gives greater access to antibiotics, allowing them to more easily penetrate the cell and/or interact with the peptidoglycan itself. You will learn more about the strategies antibiotics use to cross the cell wall in Week 3.

Can the presence of flagella be determined by a Gram stain?

The presence of flagella can be determined by a Gram stain. (Click to select) (Click to select) True False acteria 5. Rod-shaped bacteria O are called streptococci O can be either Gram-positive or Gram-negative O are always Gram-positive.

What happens if iodine is omitted in the Gram stain?

What is the function of the iodine solution in the Gram stain? If it were omitted, how would staining results be affected? It it is ommitted then, when flushed with water and the alcohol decolorized, the bacteria will come off. What is the purpose of the alcohol solution in the Gram stain?

What will happen if you Gram stain cells of an old culture?

Gram stain is reliable only on cells from cultures that are in the exponential phase of growth. Older cultures contain more ruptured and dead cells. Cells from old cultures may stain Gram negative even if the bacteria are Gram positive.

Why do old Gram positive cells stain negative?

The cells with a thick cell wall appear blue (gram positive) as crystal violet is retained within the cells, and so the red dye cannot be seen. Those cells with a thin cell wall, and therefore decolorized, appear red (gram negative).

Can all bacteria be Gram stained?

While Gram staining is a valuable diagnostic tool in both clinical and research settings, not all bacteria can be definitively classified by this technique. This gives rise to gram-variable and gram-indeterminate groups.

Why is crystal violet used in Gram staining?

The basic principle of gram staining involves the ability of the bacterial cell wall to retain the crystal violet dye during solvent treatment. Gram-positive microorganisms have higher peptidoglycan content, whereas gram-negative organisms have higher lipid content.

What is crystal violet used for?

Crystal violet is not only used as a textile dye, but also it is used to dye paper and as a component of navy blue and black inks for printing, ball-point pens, and inkjet printers. It is also used to colourize diverse products such as fertilizers, antifreezes, detergents, and leather.