What is Gram staining and why is it important?

What is Gram staining and why is it important?

The Gram stain is the most important staining procedure in microbiology. It is used to differentiate between gram positive organisms and gram negative organisms. Hence, it is a differential stain. Gram negative and gram positive organisms are distinguished from each other by differences in their cell walls.

How does gram stain work?

Gram staining is based on the ability of bacteria cell wall to retaining the crystal violet dye during solvent treatment. Bacteria cell walls are stained by the crystal violet. Iodine is subsequently added as a mordant to form the crystal violet-iodine complex so that the dye cannot be removed easily.

Why do gram negatives stain pink?

Gram staining differentiates bacteria by the chemical and physical properties of their cell walls. Gram-negative cells have a thinner peptidoglycan layer that allows the crystal violet to wash out on addition of ethanol. They are stained pink or red by the counterstain, commonly safranin or fuchsine.

Why Gram positive bacteria purple in Colour while gram negative are red?

Whereas the gram positive bacteria stain violet as a result of the presence of a thick peptidoglycan layer in the walls of their cell, the gram negative bacteria stain red, due to the thinner peptidoglycan layer in their cell wall (a thicker peptidoglycan layer allows for the retention of the stain, but a thinner layer …

What color is gram negative bacteria?


What is difference between gram positive and negative bacteria?

Gram positive bacteria have a thick peptidoglycan layer and no outer lipid membrane whilst Gram negative bacteria have a thin peptidoglycan layer and have an outer lipid membrane.

What diseases are caused by Gram positive bacteria?

Gram-positive cocci: Staphylococcus aureus is a gram-positive, catalase-positive, coagulase-positive cocci in clusters. S. aureus can cause inflammatory diseases, including skin infections, pneumonia, endocarditis, septic arthritis, osteomyelitis, and abscesses.

Is gram negative bacteria harmful?

As a rule of thumb (which has exceptions), Gram-negative bacteria are more dangerous as disease organisms, because their outer membrane is often hidden by a capsule or slime layer which hides the antigens of the cell and so acts as “camouflage” – the human body recognises a foreign body by its antigens; if they are …

How do you get rid of gram negative bacteria?

Gram-negative bacteria are refractory to the action of many antibiotics due to their impermeable outer membrane. An important player of the immune system is the complement system, a protein network in serum that directly kills Gram-negative bacteria through pore-formation by the Membrane Attack Complexes (MAC).

What is the best antibiotic for gram negative bacteria?

These antibiotics include cephalosporins (ceftriaxone-cefotaxime, ceftazidime, and others), fluoroquinolones (ciprofloxacin, levofloxacin), aminoglycosides (gentamicin, amikacin), imipenem, broad-spectrum penicillins with or without β-lactamase inhibitors (amoxicillin-clavulanic acid, piperacillin-tazobactam), and …

What are the characteristics of gram negative bacteria?

Characteristics of Gram-negative Bacteria Gram-negative bacteria have a characteristic cell envelope structure very different from Gram-positive bacteria. Gram-negative bacteria have a cytoplasmic membrane, a thin peptidoglycan layer, and an outer membrane containing lipopolysaccharide.

Which of the following is the example of gram negative bacteria?

The gram-negative bacteria include the model organism Escherichia coli, as well as many pathogenic bacteria, such as Pseudomonas aeruginosa, Chlamydia trachomatis, and Yersinia pestis.

What disease does gram negative bacteria cause?

Gram-negative bacteria cause infections including pneumonia, bloodstream infections, wound or surgical site infections, and meningitis in healthcare settings. Gram-negative bacteria are resistant to multiple drugs and are increasingly resistant to most available antibiotics.

Why is it more difficult to treat gram negative bacteria?

The bacteria, classified as Gram-negative because of their reaction to the so-called Gram stain test, can cause severe pneumonia and infections of the urinary tract, bloodstream and other parts of the body. Their cell structure makes them more difficult to attack with antibiotics than Gram-positive organisms like MRSA.

How do antibiotics kill bacteria?

Antibiotics fight bacterial infections either by killing bacteria or slowing and suspending its growth. They do this by: attacking the wall or coating surrounding bacteria. interfering with bacteria reproduction.

Why is it harder to kill gram negative bacteria?

Gram-negative bacteria don’t have a thick layer of peptidoglycan in their cell wall. Gram-negative bacteria have an outer membrane that surrounds the cell wall. This outer membrane makes gram negative bacteria harder to kill with antibiotics.

How do you treat gram negative bacteria naturally?

Some of the natural antibiotics are Garlic, Honey, Cabbage, Grapefruit seed extract, Raw apple cider vinegar, Extra virgin coconut oil, Fermented food and colloidal silver. Natural antibiotics help to kills gram-positive and gram-negative bacteria.

Is Staph A gram negative bacteria?

Staphylococci are gram-positive aerobic organisms. Staphylococcus aureus is the most pathogenic; it typically causes skin infections and sometimes pneumonia, endocarditis, and osteomyelitis.