Summary of Tests for Identification of Staphylococci

Question 1

Catalase principle

Answer 1

Enzyme catalase converts 3% hydrogen peroxide (H2O2) to oxygen & water. Immediate
bubbling.

Question 2

Coagulase principle

Answer 2

Enzyme coagulase causes coagula-tion (tube test) or agglutination (slide test) in plasma

Question 3

Slide agglutination tests for S. aureus principle

Answer 3

Agglutination of latex beads coated with fibrinogen & abs to protein A(protein in cell wall of S. aureus).

Question 4

Mannitol salt agar (MSA) principle

Answer 4

Fermentation of mannitol results in color change from pink to yellow.

Question 5

Novobiocin susceptibility principle

Answer 5

Organisms resistant to novobiocin grow to edge of disk.

Question 6

Catalase key reaction

Answer 6

Staphylococci pos. Streptococci & enterococci neg

Question 7

Coagulase key reaction

Answer 7

S. aureus pos

Question 8

Slide agglutination tests for S. aureus key reaction

Answer 8

S. aureus pos

Question 9

Mannitol salt agar (MSA) key reaction

Answer 9

S. aureus pos

Question 10

Novobiocin susceptibility key reaction

Answer 10

S. saprophyticus is resistant. Other CNS susceptible