Lecture 6. Colony morphology

α-hemolysis

Partial clearing of blood that results in a green discoloration of the medium

β-hemolysis

Complete clearing of blood cells around the colonies

What type of hemolysis is this?

Beta hemolysis

What type of hemolysis is this?

Alpha hemolysis

What type of hemolysis is this?

Gamma hemolysis

Swarming edges of colonies are described as:

Hazy blanket of growth on the media surface (ex: Proteus spp.)

Yeast colony edges are described as:

Creamy white to yellowish with “feet” or “pedicules”

What are the types of colony elevation?

• Raised

• Convex

• Flat

• Umbilicate

• Umbonate

Umbilicate elevation

Convex with depressed center (pitting S. pneumoniae if no polysaccharide capsule)

Umbonate elevation

Raised or bulging center, convex

What pigment does Pseudomonas aeruginosa give off?

Green or green metallic sheen (“oil slick”)

The microbiologist should never inhale odor directly from the plate

True

P. aeruginosa gives off what kind of odor?

Fruity or grapelike