BIO 304 Lab Worksheet 5 Spring 2006
NAME______________________________________________
Coverage: Ex 46,
47:
What was the source of the inoculum for the MSA plate? Skin
What is MSA, and why is it chosen as a selective medium for skin normal flora?
Mannitol salt agar is a selective and differential medium that selects for organisms that tolerate high salt. Since the skin can be dry and salty, it is used as a selective medium for skin normal flora
Give examples of other types of skin normal flora that probably will not grow on the MSA plate.
Propionibacterium, corynebacterium, yeast, mites: all are not suited to grow on the MSA plate
Describe the characteristics of one of the colonies isolated on the MSA plate:
colony pigment
colony diameter (mm)
colony margin
cell morphology
Gram reaction
cell arrangement
Name 4 species that can be found in a throat culture:
Neisseria, strep, haemophilus, staph
What is the predominant, or major species found in the throat culture?
streptococci
What is hemolysis? breaking open RBCs
Describe the three types of hemolytic reactions that can be observed on a blood agar plate:
alpha: greening or incomplete
beta: clearing or complete
gamma: no reaction
Is a blood agar plate selective or differential? differential
Describe the characteristics of one of the colonies isolated on the blood agar plate:
colony pigment
colony diameter (mm)
colony margin
cell morphology
Gram reaction
cell arrangement
What are ways that can be used to differentiate between Staphylococci and Streptococci?
Staph: G+ cocci in clusters, coagulase +, catalase +
Strep: G+ cocci in chains, catalase -