Enterotube Review and Practice

MCB2010L

Aerobic vs. Anaerobic chambers

• The first 4 chambers were sealed and contain anaerobic reactions.

• The last 8 chambers contain a small window covered with plastic. We used the broken-off loop tip to puncture the plastic, allowing air to enter the chambers.

WINDOW

Metabolism

S S S S S

Sulfur/ AA

AA AA

S = sugar metabolism

AA = amino acid

S/ AA AA

Enzyme activity (urease)

GLU-GAS, Chamber #1

• The GLU Gas chamber MUST have a postive reaction change in color) or test is useless.

• This test is for ENTERObacteria (ENTEROtube) and all have a positive reaction in chamber #1.

GLU-Gas: Gas production

Gas production:

The pressure of the gas caused the wax to separate from the agar.

Sometimes the gas bubble appears at the bottom, depending the position of tube during incubation.

The first 3 chambers have a wax layer to show if gas is produced.

Indole Test

• H2S/ IND chamber.• Liquid indole injected.• This shows a positive

result.• The test station would

say: “Assume indole test

positive” or “Assume indole test

negative”. Red color liquid

Reading Tube

GLU/ Gas- GLU-Yellow is +, Orange is -

Gas is + if wax separates from agar, or is pushed up & swollen.

LYS- Any degree of purple is +

ORN- Any degree of purple is +

H2S/IND- H2S is the color. Dark Brown/ Black is +

IND is the injected drop. Red is +, no color change is - (you’ll be told result).

ADON, LAC, ARAB, SORB- Yellow is +, orange is - & pink is -

VP- Ignore. We don’t do this test.

DUL/PA- Green = dulcitol is - , PA is -

Yellow = dulcitol is +, PA is -

Brown/ Black = dulcitol is - , PA is +

UREA- Purple or Hot Pink is +

CIT- Blue is +

Practice 1

# 6

Assume the agar has swelled and pushed wax up in GLU-Gas chamber.

Assume Indole Test is Negative.

Practice 2

Assume the agar & wax position is unchanged in GLU-Gas chamber.

Assume Indole Test Positive.

Practice 3

Assume the wax separated from the agar, leaving an air space.

Assume Indole Test is Negative.

Practice 4

Assume gas production in GLU-Gas chamber.

Assume Indole Test is negative.

Answers to Practice

Normally, you would be able to flip eneterotube over to look for gas in GLU-Gas chamber.

#1 32341

#2 24540

#3 33007

Although sugar chambers appear pink, rather than orange, they are not considered the positive color change of yellow.

#4 36261

Looking up code & Confirmatory tests

• The next step is to look up the 5 digit code in the purple binder.• Confirmatory Tests are used to distinguish among possible choices for the same 5 digit number.• You will be given Confirmatory Test results & be able to choose.

5 digit code Possible bacteria

Confirmatory test 1

Confirmatory test 2

22161 RAF VP

bacteria 1 + +

bacteria 2 - +

bacteria 3 V(70%) -

5 digit code Possible bacteria

Confirmatory test 1

Confirmatory test 2

22161 RAF VP

bacteria 1 + +

bacteria 2 - +

bacteria 3 V(70%) -

1.) Confirmatory Tests show that RAF = V(70%) and VP = -. Which bacteria would it be?

2.) Confirmatory Tests show RAF = +, and VP = +. Which bacteria would it be?

3.) Confirmatory Tests show RAF = - and VP = +. Which bacteria would it be?

Answers to Confirmatory Tests

1. Bacteria 3

2. Bacteria 1

3. Bacteria 2