What is a Gram stain test used for?
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What is a Gram stain test used for?
The Gram stain method is one of the most commonly used techniques to quickly diagnose bacterial infections. A Gram stain is a test used to help identify bacteria. The tested sample can be taken from body fluids that do not normally contain bacteria, such as blood, urine, or cerebrospinal fluid.
What tests are used to identify Gram positive bacteria?
Tests used to identify Gram Positive Bacteria
- Catalase Test.
- Mannitol Salt Agar (MSA)
- Blood Agar Plates (BAP)
- Streak-stab technique.
- Taxos P (optochin sensitivity testing)
- Taxos A (bacitracin sensitivity testing)
- CAMP Test.
- Bile Esculin Agar.
What does many gram-positive rods mean?
A gram-positive bacillus doesn’t have an outer cell wall beyond the peptidoglycan membrane. This makes it more absorbent. Its peptidoglycan layer is much thicker than the peptidoglycan layer on gram-negative bacilli. Gram-positive bacilli are shaped like rods.
Why is it important to know if a bacteria is gram-positive or negative?
Gram-positive bacteria cause tremendous problems and are the focus of many eradication efforts, but meanwhile, Gram-negative bacteria have been developing dangerous resistance and are therefore classified by the CDC as a more serious threat.
How do you perform a Gram stain test?
There are six basic steps:
- Apply a smear of bacteria on to a slide.
- Add about 5 drops of Hucker’s Crystal Violet to the culture.
- Add about 5 drops of iodine solution to the culture.
- Tilt slide and decolorize with solvent (acetone-alcohol solution) until purple color stops running.
- Add about 5 drops of Safranine O.
What diseases are caused by Gram positive bacteria?
Gram-positive infections include methicillin-resistant Staphylococcus aureus (MRSA), strep infections, and toxic shock. Gram-negative infections include salmonella, pneumonia, urinary tract infections, and gonorrhea.
What color is Gram-positive?
A Gram stain is colored purple. When the stain combines with bacteria in a sample, the bacteria will either stay purple or turn pink or red. If the bacteria stays purple, they are Gram-positive. If the bacteria turns pink or red, they are Gram-negative.
What Colour is Gram-positive?
Hans Christian Gram developed the staining method in 1884. The staining method uses crystal violet dye, which is retained by the thick peptidoglycan cell wall found in gram-positive organisms. This reaction gives gram-positive organisms a blue color when viewed under a microscope.
Which of the following test differentiates between Staphylococcus aureus and staphylococci?
Tests for clumping factor, coagulase, hemolysins and thermostable deoxyribonuclease are routinely used to identify S aureus. Commercial latex agglutination tests are available.
What biochemical tests are used to identify Staphylococcus?
3.1. Biochemical tests used to confirm S. aureus were coagulase test, catalase test, indole production, methyl red test, Voges-proskauer reaction, urease production, citrate utilization and sugar fermentation [12].
