3/29 Flashcards
What is a complex, selective, and differential medium
Eosin methylene blue agar
What contains a digest of gelatin, lactose, and the dues eosin and methylene blue
Eosin methylene blue agar
What is the purpose of the two dues in EMB
1) inhibit growth of most gram positive organisms
2) react with lactose fermenters whose acid products turn the growth black
What do lactose non fermenters appear like
Retain their normal color or take the coloration of the medium
What is EMB agar used for
Isolation of fecal coliforms
Fermentation of lactose by the coliform produces what
Shiny green appearance to the growth
Poor or no growth in EMB is
Gram positive
Good growth on EMB is
Gram negative
Growth is pink in EMB
Possible coliform
Growth is dark in EMB
Probable coliform
Growth is colorless in EMB
Noncoliform
What does Columbia CNA do
Allows growth of gram positive organisms and inhibits growth of gram negative organisms
What act as selective agents against gram negative organisms in Columbia CNA
Antibiotics colistin and nalidixic acid
What does the sheep blood part of Columbia CNA do
Differentiation of gram positive organisms based on hemolytic reaction
What is Columbia CNA agar used to do
Isolate staphylococci, streptococci, and enterococci
What are the only organisms that grow well on the Columbia CNA agar
Gram positive
What does the NA plate will serve as what
A comparison for growth quality on the Columbia CNA with 5% sheep blood agar plate
Poor or no growth on Columbia CNA
Probable gram negative organism
Good growth with clearing of medium in Columbia CNA
B hemolytic
Good growth with greening of medium in Columbia CNA
Probable ~ hemolytic
Good growth with. No change of medium in Columbia CNA
Probable y hemolytic
What does mannitol salt agar contain
The carbohydrate mannitol, 7.5% sodium chloride, and the pH indicator phenol red
When is phenol red yellow
Below 6.8
When is phenol red red
7.4 to 8.4
When is phenol red pink
8.4 and above
What does mannitol provide
Substrate for fermentation and makes the medium differential
What thrive on mannitol salt agar
Staphylococci
What does phenol red indicate
Whether fermentation with an acid end product has occurred
What is mannitol salt agar used for
Isolation and differentiation of staphylococcus
