Urine Specimen Unknown

Question 1

What are the common organisms associated with UTI’s? How many at once?

Answer 1

E. Coli (most common!)
Proteus
Pseudomonas
Enterococcus
Staphylococcus saprophyticus
Enterobacter
Usually cause by a single microorganism at once. But occasionally multiple.

Question 2

Why do we want to collect a midstream piss for a sample to test for a UTI?

Answer 2

To avoid as much contaminating bacteria as possible like from urethra.

Question 3

What does a high number of 1 or 2 micro bacteria in a sample indicate? What about more than 2?

Answer 3

1 or 2 types at 10^5/mL or higher indicates UTI. More then 2 results in poorly collected sample.

Question 4

What is MacConkey Agar used for? How?

Answer 4

Differential medium.
Contains lactose: lactose fermenting colonies will turn reddish-purple, non-lactose fermenting colonies stay colorless.
Contains pH indicator.
Selective medium too!
Contains dyes and bile salts that inhibit Gram-Positive organism and Gram-negative cocci.

Question 5

What is blood agar used for? How?

Answer 5

Not selective medium.
Is differential for hemolysis. But not super helpful as characteristic vary amount intestinal isolates.

Question 6

Both Enterococcus and Staphylococcus are gram positive cocci. What makes them different?

Answer 6

Staphylococcus is catalase positive, enterococcus is catalase negative.

Question 7

If you test for indole production for a gram negative rod and it’s positive, what’s likely the bacteria?

Answer 7

E. Coli

Question 8

What is the MR/VP test?

Answer 8

Two different pathways to ferment glucose.
E.Coli uses mixed acid fermentation pathway ending in acidic end products.
Enterobacter and Klebsiella use the butanediol pathway, ending with product acetoin and less acidic pH.

Question 9

What will the citrate slant test for?

Answer 9

Ability to use citrate as sole source of carbon and energy.
E. Coli is negative
Enterobacter and Klebsiella are positive.

Question 10

What is the Motility agar deep test?

Answer 10

Tests an organisms motility.
Enterobacter is motile
Klebsiella is not.

Question 11

If you gram negative rod is not lactose positive, what is it?

Answer 11

Either Pseudomonas or Proteus.
Pseudomonas typically sweet smell and green. Oxidase positive
Proteus strong odor and swarms of non selective media. Oxidase negative