What is the purpose of doing an acid fast stain?

It is a differential stain used to detect cells capable of retaining a primary stain when treated with acid alcohol.

What bacteria is an acid fast stain used to identify?

Mycobacterium

What are the 3 primary steps involved in doing an acid fast stain?

1. Stain with carbolfuchsin
2. Decolorize with alcohol
3. Counterstain with methylene blue

What three organisms would be positive for a capsule stain?

Bacillus anthracis, Streptococcus pneumoniae, Klebsiella pneumoniae

What is a capsule stain?

A differential stain which selectively stains external capsules surrounding bacterial cells.

What is the purpose of doing an endospore stain?

To detect the presence, shape, and location of endospores in bacterial cells.

What are the two main genera identified by the presence of endospores?

1. Bacillus
2. Clostridum

What is the procedure for endospore stain?

1. Stain with malachite green
2. Heat fix
3. Decolorize with water
4. Counterstain with safranin

Blood Agar is selective for...

Streptococcus

Blood Agar is differential for...

An organism's ability to hemolyze red blood cells

Blood Agar: Alpha hemolysis

Mild or incomplete hemolysis

Blood Agar: Beta hemolysis

Complete hemolysis

Blood Agar: Gamma Hemolysis

No hemolysis

Mannitol Salt Agar is selective for...

Staphylococcus aureus

Mannitol Salt Agar is differential for...

An organism's ability to ferment the carbohydrate mannitol.

Color of a pathogen on Mannitol Salt Agar plate?

Yellow

Color of nonpathogen on Mannitol Salt Agar plate?

Red

Eosin Methylene Blue (EMB) Agar is selective for...

Members of enteric bacteria (Gram negative rods)

Eosin Methylene Blue (EMB) Agar is differential for...

An organism's ability to ferment lactose.

Color of nonpathogen on EMB Agar?

Green

Color of weak pathogen on EMB Agar?

Pink

Color of strong pathogen on EMB Agar?

White

MacConkeys Agar is selective for....

Enteric gut bacteria

MacConkeys Agar is differential for...

An organism's ability to ferment lactose

Color of nonpathogen on MAC Agar?

Pink

Color of pathogen on MAC Agar?

White

Selective Media

Suppresses the growth of some organisms and promotes the growth of others (Gram + or Gram -)

Differential Media

Allows you to differentiate between two types of bacteria (fermentation of lactose.)