Lab 6- Blood Agar & Antimicrobial Disk Diffusion Lab Content

Question 1

What is blood added to?

Answer 1

TSA, tryptic soy agar

Question 2

what is blood agar and what is it used for

Answer 2

• solid growth medium that contains red blood cells (5% sheep blood)
• used to identify bacteria and classify them based on their ability to produce hemolysins, enzymes that damage red blood cells

Question 3

why is blood added to TSA

Answer 3

to identify bacteria that lyse red blood cells-hemolysis

Question 4

What does lyse mean?

Answer 4

break down the membrane of the cells, compromise its integrity.

Question 5

what do hemolysins do?

Answer 5

destroy red blood cells and hemoglobin

Question 6

What are the hemolysins produced by streptococci called?

Answer 6

streptolysins

Question 7

Streptolysin O

Answer 7

oxygen-labile and is immunogenic, meaning the body produces antibodies against it

Question 8

Streptolysin S

Answer 8

oxygen stable, nonimmunogenic, meaning the body doesn’t produce antibodies against it.

Question 9

type of hemolysis: Beta hemolysis

Answer 9

• complete or true lysis of red blood cells
• a clear zone around growth
• streptococcus pyogenes

Question 10

Type of hemolysis: Alpha hemolysis

Answer 10

• reduction of the red blood cell hemoglobin to methemoglobin in the medium surrounding the colony
• This causes a green or brown discoloration in the medium
• Streptococcus pneumoniae

Question 11

Type of hemolysis: Gamma hemolysis

Answer 11

• indicates the lack of hemolysis
• no reaction in the surrounding medium
• Staphylococcus epidermidis

Question 12

What is the Antimicrobial Susceptibility Test (AST) important for?

Answer 12

important for treating infectious diseases and monitoring antimicrobial resistance in various pathogens. several methods of AST. Allows to selection of antibiotics for patients, get information of microbial resistance of public health, and to personalize medicine.