Pre-laboratory 1. What role does a bacterial capsule play in infection? What kin
ID: 3164560 • Letter: P
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Pre-laboratory 1. What role does a bacterial capsule play in infection? What kind of culture media, atmospheric, and incubation conditions are best for cultivating streptococci? 2. 3. Why is blood agar considered a differential medium? 4. What is the function of a candle jar or CO2 chamber? Describe the hemolysis produced by alpha-hemolytic, beta-hemolytic, and nonhemolytic streptococci. 5. What type of hemolysis is displayed by the group of streptococci that are most pathogenic for human beings? To what Lancefield group do these usually belong? 6. 7. Is the normal flora beneficial to the host? Explain.Explanation / Answer
Answer 1 The capsule enhances bacterial capability to cause disease since it prevents its phagocytosis by macrophages. It is considered a virulence factor
Answer 2: Streptococci is cultured on a blood agar, at 35 degrees celsius for 24- 48 hours , and atmospheric conditions should be reduced oxygen and increased CO2
Answer 3: blood agar is called a sdifferential media because it differentiates the organisms on the basis of hemolysins they produce for eg alpha, beta or gamma
Answer 4: The candle flame will consume most of oxygen and produce high amount of carbondi oxide in the chamber. As a resukt conditions for the growth of microaerophilic organisms wll be created
Answer 5: Hemolysins are proteins or enzymes that have the ability to lyse red blood cells (RBCs). Alpha hemolysins cause a partial lysis of the RBCs, resulting in a darkening of the media around a colony on blood agar. Beta hemolysins produce a complete lysis of the RBCs, resulting in the formation ofclearing zone around the colony. nn hemolytic bacteria will not produce any lind of hemolysins.
Answer 6: Beta hemolysis whch is a complete destruction of red blood cells is a sign of a pathogenic streptococcus. Most of pathogenic streptococcus belongs to Group A.
Answer 7: Normal flora is beneficial to the host since it will compete with invaders for space and nutrients. Also it will lower pH and create conditions so that other bacteria can't grow. It also produces compounds called bacitrocins to kill other bacteria.
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