Lab Exercise 17:Biochemical Differentiation of some

Medically Important Gram-negative Bacilli

MacConkey Agar

Left: Shigella

- result

Right: Escherichia

+ result

Carbohydrate Fermentation TestsGlucose w/ Durham Fermentation Tube

Carbohydrate Fermentation TestsSucrose Fermentation

Triple Sugar Iron

-/+/+

Indole Test

broth with tryptophan

IMViC Series

Methyl Red TestIMViC Series

Voges-Proskauer Test

αLeave uncapped for 15-20 minutes……..

IMViC Series

MRVP broth

Citrate Utilization Test

- +

IMViC Series

Urease Test

Slow positive

Negative result (acidic)

Uninoculated urea agar

Positive result (alkaline)

Motility Test

MacConkey agar

1. Which plate could have E. coli on it?

2. Which plate shows the presence of a lactose-fermenter?

3. Which plate could have Salmonella on it?

4. Which plate shows the presence of a lactose non-fermenter?

Answers:

1. A 3. B

2. A 4. B

A

B

What is the name of the lab procedure demonstrated here?

Answer: Stabbing the butt!

Use the chart on p. 181 and or the flow chart on p. 182 of your lab manual to figure out who I am!

I M V

C

U

Answer: Shigella sonnei

I M V

C

U

Use the chart on p. 181 and/or the flow chart on p. 182 of your lab manual to figure out who I am!

Answer: Escherichia coli

I M V C

U

Use the chart on p. 181 and/or the flow chart on p. 182 of your lab manual to figure out who I am!

Answer: Serratia marcesens

Use the chart on p. 181 and/or the flow chart on p. 182 of your lab manual to figure out who I am!

I M V C

Answer: Klebsiella pneumoniae

Use the chart on p. 181 and/or the flow chart on p. 182 of your lab manual to figure out who I am!

I M V C U

Answer: Salmonella typhimurium

Use the chart on p. 181 and/or the flow chart on p. 182 of your lab manual to figure out who I am!

I M V CU

Answer: Proteus vulgaris

Use the chart on p. 181 and/or the flow chart on p. 182 of your lab manual to figure out who I am!

I M V C

Answer: Enterobacter aerogenes

U