E. Coli and Opportunistic Enterobacteriae

Question 1

General characteristics of the Opportunistic Enterobacteriacae

Answer 1

• Ferment Glucose (distinguishes them from psuedomonas)
• Oxidase Negative (distinguishes them from psuedomonas this time)
• Reduce Nitrates to nitrites
• Motile by peritrichous flagella
• Many are part of the intestinal flora
• Facultative anaerobes

Question 2

Morphology of enterobacteriacae

Answer 2

Gram- negative, facutative anaerobes

Question 3

Describe MacConkey Agar

Answer 3

Contains:

• chemicals that inhibit gram positives (bile salts and crystal violet)
• pH indicator
• and a carbohydrate source (like lactose)

Question 4

Organisms that are able to ferment lactose to acid (normal flora) produce a pH change and lead to a change in color to red/pink

Answer 4

ok

Question 5

Organisms like Shigella and Salmonella cannot ferment lactose and therefore appear as white colonies on the agar

Answer 5

ok

Question 6

Inflammatory diarrhea

Answer 6

The squirts, comes from the colon mostly, may not become all that dehydrated…also known as dysentery…the presence of blood, pus, leukocytes in material

Question 7

Chronic diarrhea…start considering AIDS

Answer 7

Diarrhea is a huge problem with AIDS pts

Question 8

What bugs are particularly suspicious when looking at diarrhea in AIDS pts

Answer 8

Mycobacterium Avium and CMV

Question 9

know diagnosis and management of diarrhea

Answer 9

ok

Question 10

Define enterics

Answer 10

any bacterium that can multiply in the GI tract

Question 11

coliforms?

Answer 11

The most common lactose-fermenting members of the enterobacteriae found in the gut

Question 12

Lactose Fermenters turn MacConkey Agar what color?

Answer 12

Red, because the pH becomes more acidic

Question 13

Organisms that don’t ferment lactose turn MacConkey Agar what color?

Answer 13

white

Question 14

Do strict anaerobes usually cause GI disease?

Answer 14

No….except for the clostrdia