What kind of media is Blood agar? What is hemolysis? Describe and tell what happ

Question

What kind of media is Blood agar? What is hemolysis? Describe and tell what happening in the media for each type of hemolysis? interpret results by observing incubated plates? Give the organism that demonstrates each type of hemolysis? What group of strep is CAMP test specifically designed for? Discuss CAMP test theory? how do you perform CAMP TEST? what is the purpose of using the staphylococcus aureus in the CAMP test? What does coagulase test media test for? what enzymes are responsible in the coagulase test? How is the test performed? Interpret results by observing the tubes? name one organism that gives a positive/negative result in coagulase test?

Explanation / Answer

Blood agar is trypticase soya agar enriched, bacterial growth medium, it contains general nutrients and 5% sheep blood. It is a kind of growth medium, it encourages the growth of bacteria, such as streptococci. Blood agar:- Blood agar contains a base containing a protein source (e.g. Tryptones), soybean protein digest, sodium chloride (Nacl), agar and 5% sheep blood.

Hemolysis:-Hemolysis is a lysis of red blood cells. Extracellular enzymes produced by certain bacterial species, lyse red blood cells in the blood agar is known as hemolysis. These extotoxin or hemolysin move towards the colony (or colonies) leads to complete or partial destruction of the red cells (RBC) in the medium and hemoglobin completly denaturates within the cells to colorless products. Sheep blood agar by Streptococci produces four types of hemolysis namely:- Alpha hemolysis, Beta hemolysis, gamma hemolysis and alpha prime or wide zone alpha hemolysis.

Types of hemolysis in the blood agar and interpreting results by observing incubated plate and organism that demonstrates each type of hemolysis :-

1. Alpha hemolysis: In the blood agar, the RBC is partially lyse to produce a greenish-gray or brownish discoloration around the colony. Reduction of RBC hemoglobin to methemoglobin causes hemolysis in the medium surrounding the colony. Streptococcus demonstrates the alpha hemolysis. Most of the alpha hemolytic streptococci are part of the normal body flora. But Streptococcus pneumoniae which is also alpha hemolytic causes serious pneumonia and other deadly infectious disease.

2.Beta Hemolysis: It causes the lysis of Red Blood Cells completely, causes a clearing of blood from the medium under and surrounding the colonies e.g. Group A beta hemolytic streptococci-Streptococcus pyogenes and Group B, beta hemolytic streptococci-Streptococcus agalactiace. All the colonies are gram stained.

3. Gamma or non hemolysisAlpha prime or wide zone alpha hemolysis: A small zone of intact erythrocytes immediately adjacent to bacterial colony, with a zone of complete red-cell hemolysis. It is characterized by the abscence of discolored RBC. In this group streptococci are usually not pathogenic ex. Enterococcus faecalis.

4.Alpha prime or wide zone alpha hemolysis: Immediately adjacent to bacterial colony a small zone of intact erythrocytes is formed, where zone of red-cell completely hemolysed, surrounding the zone of intact erythrocytes.

CAMP("Christie–Atkins–Munch-Petersen") test specifically designed for Group B -streptococci . Because CAMP factor, enlarges the area of hemolysis formed by -hemolysin from Staphylococcus aureus. CAMP factor gene is found in several groups of streptococci, including group "A".It is used to identify group "B",

Purpose of CAMP test is used in identification of both S. agalactiae and many gram-positive rods, including Listeria monocytogenes.

coagulase test media test the presence of bound coagulase or clumping factor, which is attached to the cell walls of the bacteria. Enzymes responsible in the coagulase test is   protease, protease used to convert fibrinogen, which results in clotting of the blood.

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