TELL ME: AGAR

Question 1

Lactose Pos: Green sheen,
purplish, and brownish amber

Answer 1

EMB

Question 2

Lactose positive: Dark Pink

Answer 2

MAC

Question 3

Isolation and differentiation of Salmonella and Shigella spp. from other gram negative enteric bacill

Answer 3

XLD

Question 4

Indicator:
• Phenol red: acidification
• Ferrous sulfate: H2S formation
Slant: sucrose and lactose Butt: glucose

Answer 4

Triple Sugar Ion Agar (TSI)

Question 5

Ability to ferment glucose, lactose, and sucrose
• Produce hydrogen sulfide

Answer 5

Triple Sugar Ion Agar (TSI)

Question 6

Test the ability of the organism to produce the enzyme tryptophanase and deaminate tryptophan to indole, pyruvic acid, and ammonia

Positive: pink to wine colored ring after addition of reagents
Negative: yellow color

Answer 6

Indole Production

Question 7

Positive: red color (when medium reaches a pH of 4.5)
• Negative: yellow color

Answer 7

Bacteria metabolizes glucose by the mixed acid pathway leading to a decrease in the pH of the medium

Question 8

Detects end products of glucose fermentation by the butylene glycol pathway

Positive: red color (presence of acetoin)
• Negative: yellow color

Answer 8

Voges Proskauer

Question 9

Determines if an organism can utilize sodium citrate as a sole source of carbon
• Simmons citrate agar
• Indicator: bromthymol blue

Answer 9

Citrate Utilization Test

Question 10

Determine the ability of the organism to reduce nitrate to nitrite

   • Positive: red color

Answer 10

Nitrate reduction

Question 11

Demonstrate motility
• Positive: haziness along the stab line

Answer 11

Motility test

Question 12

Detecting slow lactose fermenters
• Positive: yellow color within 20 minutes-24 hours
• Negative: colorless after 24 hours

Answer 12

ONPG (beta galactosidase test)

Question 14

Determine the ability of an organism to oxidatively deaminate phenylalanine to phenylpyruvic acid

Answer 14

Phenylalanine deamination

Question 15

Selective for N. gonorrohoe & N. meningitidis; Supports the growth of Francisella spp. & Brucella spp.

Answer 15

Modified Thayer-Thayer Martin Agar

Question 16

Selective differentiation of staphylococci

Answer 16

MSA

Question 17

Rapid identification of Proteus spp.
• Indicator: phenol red

Answer 17

Rapid Urease Test

Question 18

Detecting slow lactose fermenters

Positive: yellow color within 20 minutes-24 hours
• Negative: colorless after 24 hours

Answer 18

ONPG (beta galactosidase test)

Question 20

Used for isolation of Haemophilus influenzae from the respiratory secretion of patients with CF

Answer 20

oHorse blood-bacitracin agar