What is the Gram stain useful for?
What are the gram staining techniques?
1.Apply primary stain- (crystal violet) all bacteria are stained purple by this basic dye
2. Apply mordant Gram's iodine- the iodine combines with the crystal violet in the cell to form a crystal violet-iodine (CV-1 complex)
3. Apply decolorizing agent (ethanol). The primary stain is washed out of some bacteria (decolorized) and some are unaffected.
4. Apply secondary stain or counterstain (safranin) this basic dye stains the decolorized bacteria red
What is the most important determining factor in the procedure of Gram staining?
Gram-negative bacterial cell walls contain a__________ layer of peptidoglycans surrounded by an outer layer of lipoproteins, phospholipids and lipopolysaccharides.
Iodine react with the dye in the ___________to form CV-1 that is ________ than the crystal violet that entered the cell.
The alcohol decolorizing agent ________________ the cell wall of the ___________ cells.
Why are cells less than 24 hours better?
Preparation of Gram staining:
Gram staining procedure:
1. starting with fixed smear cover the smear with crystal violet for 1 minute
2. gently wash off crystal violet with water until it runs clear
3.cover the smear with Gram's iodine for 30 seconds
4.gently wash smear with water
5. decolorize with ethanol
6.gently wash off ethanol
7.cover the smear with safranin for 1 minute
8. wash the smear with water
9. blot it dry
What are some common sources of Gram staining error?
Bacteria: Staphylococcus epidermidis
name the morphology and arrangement and gram stain result
Considering you can't identify bacteria from a Gram stain, why might a physician perform a Gram stain on a sample before prescribing an antibiotic?