Staphylococcus

Question 1

Gram staining type of Staphylococci

Answer 1

Gram positive

Question 2

Characteristics of staphylococci

Answer 2

• grape appearance
• nonmotile
• non spore formation
• facultative anaerobe

Question 3

How to differentiate between Staphylococci and Streptococci?

Answer 3

Staphylococci are Catalase positive

Question 4

How to differentiate S.aureus from other Staphylococcus species?

Answer 4

S. Aureus is Coagulase positive

Question 5

What kind of diseases can be caused by Staphylococci?

Answer 5

Toxin mediated -> food poisoning, scalded skin syndrome
Cutaneous infections -> Carbuncles, Folliculitis, Impetigo
Bacteremia

Question 6

What are the virulence factors of S. aureus?

Answer 6

Toxins, structural components (Protein A), hydrolytic enzymes, capsule

Question 7

S. Aureus on which Agar?

Answer 7

Blood agar

Question 8

Appearance on media of staphylococci

Answer 8

Circular, opaque, smooth colonies, hemolysis on blood agar
S. Aureus -> golden color pigments

Question 9

How is the Catalase test performed?

Answer 9

Performed by adding one drop of 3% H2O2 -> positive if there air bubbles

Question 10

What does Coagulase do?

Answer 10

It converts Fibrinogen into fibrin

Question 11

How can be the transmission of MRSA?

Answer 11

Hospital aquired or community associated (USA300 strain)

Question 12

Which species of Staphylococci produces a Biofilm?

Answer 12

S. Epidermidis

Question 13

Virulence factors of S. Epidermidis

Answer 13

Biofilm + associated protein
Polysaccharide Intercellular Adhesion
Enterotoxin like toxin
Delta toxin

Question 14

Transmission of S. epidermidis

Answer 14

Hospital associated (nosocomial) or medical devices associated (catheter)

Question 15

S. Saprophyticus

Answer 15

UTI in healthy sexually active young women
Novobiocin resistance

Question 16

Answer 16

S. Aureus