Media Types Exam 2

Question 1

Blood agar

Answer 1

Enriched: helps growth
Differential by hemolysis
Beta: complete
Alpha: partial (green color)
Gamma: no hemolysis ( no change in color)

Question 2

Catalase test

Answer 2

Three methods used to determine if
Strep to or staphlo

Bubble=>positive => staphyl
No bubbles => negative=> strepto

Question 3

Citrate

Answer 3

Differential media
Blue is positive for citrate utilization
Green is negative

Question 4

Fermentation tubes of sugar

Answer 4

Differential for sugar use

1. Growth (valid test)
2. Color: yellow (positive) red (negative)
3. Gas, yes or no

Question 5

H2S

Answer 5

H2s differential
Black media is positive for h2s

No black media is negative

Question 6

Urea

Answer 6

Differential
Pink color is positive for urease so
Any other color is negative for urease

Question 7

EMB (eosin methylene blue)

Answer 7

Selective for gram -

Differential for lactose fermentation
Opaque colored colony, is a lactose fermenter
Clear colony does NOT ferment lactose

Question 8

Mac (macconkeys agar)

Answer 8

Selective for gram -

Differential for lactose fermentation
If pink colored colony after 24 hours, positive lactose fermentation
If not pink colony after 24 hours, negative lactose fermentation

Question 9

TSA +

Answer 9

Selective for gram positive bacteria

Question 10

TSI agar (triple sugar iron agar)

Answer 10

Differential media 5 things

1. Glucose (yellow in part of tube)
2. Lactose (yellow all over)
3. Sucrose (yellow all over)
4. Gas (is or is not produced)
5. H2S( is or is not black media)

Question 11

OF glucose (oxidation vs fermentation)

Answer 11

Differential for glucose use
Two test tubes used, one covered with oil for anaerobic conditions

Oxidative, only tube without oil yellow
Fermenative, both tubes yellow
Glucose not used, neither tube yellow

Question 12

MR VP (metal red, Voges-Proskauer)

Answer 12

Differential
MR
+ red color
- not red

VP
+ pink or red color
- not pink or red

Question 13

TSB with 6.5% salt

Answer 13

Selective for growth in high salt concentration

Question 14

Decarboxilase of ornithine or lysine

Answer 14

Differential media for amino acid use
- yellow or no color change
+ purple color

Question 15

MUG

Answer 15

Differential
Used to detect E. Coli in water
E. Coli will fluoresce under UV light.

Question 16

Blood agar with PEA

Answer 16

Selective fro gram + bacteria

Differential fro hemolysis

Question 17

Nitrate reduction

Answer 17

If at first a pink/red color observed positive

Zinc added
Red or pink color is negative
No color change is positive