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Question 1

Colonies have a unique texture with swirling, filamentous
projections, resembling Medusa’s snakes or a lion’s mane.

Answer 1

“Medusa head” or “lion’s face”
(Bacillus anthracis)

Question 2

The bacteria are highly motile and spread out across the agar surface in concentric circles rather than forming
isolated colonies.

Answer 2

Swarming
(Proteus sp.)

Question 3

The colonies of these bacteria have irregular,uneven margins, often described as having a “frosted glass” appearance.

Answer 3

Rough edges
(Diphtheroids)

Question 4

develop a star-like shape or extend projections
(“feet” or “pedicles”) from the main body of the colony.

Answer 4

“Star” or “colonies with feet”
(yeast)

Question 5

Colonies have jagged, wavy margins. They may also be associated with a distinct fruity smell and a greenish pigment.

Answer 5

Serated edges
(Pseudomonas aeruginosa)

Question 6

Colonies have distinctive, lobed shape and a convoluted, textured surface that resembles a molar tooth.

Answer 6

“Molar tooth”
(Actinomyces israelii)

Question 7

Describes side profile or height of the colony on an agar surface; should be determined by tilting the culture plate and looking at the side of the colony

Answer 7

Elevation

Question 8

determined by touching the colony with a sterile loop; tells about the internal physical makeup of the colony

Answer 8

Consistency and Texture:

Question 9

Colonies are dry and breaks apart easily or crumbles (Example: Nocardia spp.)

Answer 9

Brittle or splinters

Question 10

Colony feels smooth and moist, and the entire mass can be easily picked up with the loop. Common among pathogenic bacteria.

Answer 10

Creamy or buttery

Question 11

Occasionally, the entire colony adheres (sticks) to the loop; surface has a waxy appearance and a dull finish (Example: Diptheroids)

Answer 11

Dry and waxy

Question 12

Rough and dull; cauliflower appearance (Example: Mycobacterium spp.)

Answer 12

Rough and wanty

Question 13

Wet & sticky colony; when touched with a loop, a “string” or thread of mucus-like material is often pulled away
(Example: Streptococcus pneumonia)

Answer 13

Viscous/ Mucoid

Question 14

Surface of the colony is even, glossy, and shiny

Answer 14

smooth

Question 15

The colony has a tangled, thread-like or hair-like appearance at the edges or throughout the colony

Answer 15

Filamentous

Question 16

Covered with ridges and folds

Answer 16

Wrinkled

Question 17

Describes the ability of a bacterial colony to lyse, or break down, red blood cells on a blood agar plate (BAP)

Answer 17

Hemolytic Pattern:

Question 18

•Greenish/brownish discoloration around the colonies.
•Partial lysis of red blood cells, which results from the oxidation of hemoglobin

Answer 18

Alpha (a) Hemolysis
(Streptococcus pneumoniae)

Question 19

•A clear, transparent zone or halo around the colonies.
•Complete lysis of red blood cells due to bacterial toxins
called hemolysins.

Answer 19

Beta (B) Hemolysis
(Streptococcus pyogenes)

Question 20

•No change in the color of the agar around the colonies.
•Indicates a lack of hemolysis;

Answer 20

Gamma (y) Hemolysis
(Enterococcus faecalis)