question
CNA blood agar is used to ...
answer
SPECIFICALLY GROW gram positive organisms such as staphylococci, streptococci and enterococci
question
What is in columbia CNA blood agar?
answer
-digested casein
-digested animal tissue
-beef extract
-yeast extract
-corn starch
-sheep blood
-digested animal tissue
-beef extract
-yeast extract
-corn starch
-sheep blood
question
the presence of all these compounds makes the media ...
answer
EXTREMELY NUTRIENT RICH which should allow for the growth of a wide variety of organisms except ... gram negative
question
C =
NA =
NA =
answer
Colistin
Nalidixic acid
Nalidixic acid
question
colistin and nalidixic acid are ANTIBIOTICS that act as SELECTIVE AGENTS AGAINST ...
answer
gram negative organisms
question
Therefore, CNA blood agar is a ...
answer
SELECTIVE media
-ONLY ALLOWS growth of GRAM POSITIVE species
-ONLY ALLOWS growth of GRAM POSITIVE species
question
Colistin:
answer
-can insert into the outer membrane of the gram negative bacterial cell wall
-the insertion of the colistin into the outer membrane DISRUPTS the INTEGRITY of the OUTER MEMBRANE, which can lead to bacterial cell lysis
-the insertion of the colistin into the outer membrane DISRUPTS the INTEGRITY of the OUTER MEMBRANE, which can lead to bacterial cell lysis
question
Nalidixic acid:
answer
-disrupts bacterial enzymes involved in DNA replication, thereby INHIBITING DNA SYNTHESIS
-gram negative bacteria are MORE SENSITIVE to nalidixic acid than gram positive bacteria
-gram negative bacteria are MORE SENSITIVE to nalidixic acid than gram positive bacteria
question
the SHEEP BLOOD in the columbia CNA agar also makes the media ...
answer
DIFFERENTIAL
-different bacteria will show DIFFERENT red blood cell HEMOLYSIS PATTERNS when grown on agar that contains sheep's blood
-different bacteria will show DIFFERENT red blood cell HEMOLYSIS PATTERNS when grown on agar that contains sheep's blood
question
POOR or NO growth
answer
-organism inhibited by colisitin + nalidixic acid
GRAM NEGATIVE
GRAM NEGATIVE
question
GOOD growth with CLEARING of blood
answer
growth = gram positive
-organism not inhibited by antibiotics and can completely lysis RBCs
β-HEMOLYTIC
-organism not inhibited by antibiotics and can completely lysis RBCs
β-HEMOLYTIC
question
GOOD growth with GREENING of agar
answer
growth = gram positive
-organism not inhibited by antibiotics and can partially lysis RBCs
α-HEMOLYTIC
-organism not inhibited by antibiotics and can partially lysis RBCs
α-HEMOLYTIC
question
GOOD growth with NO change in color of the agar
answer
growth = gram positive
-organism no inhibited by antibiotics but cannot lysis RBCs
𝞬-HEMOLYTIC
-organism no inhibited by antibiotics but cannot lysis RBCs
𝞬-HEMOLYTIC
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