M4: Staphyloccoci & Disease

Question 1

What are some species of Staphylococcus of humans origin

Answer 1

• S. epidermidis
• S. haemolyticus
• S. lugdunensis

Question 2

What are the main diagnostic features of Staphylococcus aureus? (4)

Answer 2

• Colonies often pigmented
• Production of extra-cellular coagulase (tube test).
• Production of nucleases that break down DNA
• Production of cell surface-associated enzyme

Question 3

Give some examples of pyogenic infections caused by Staph. aureus (4)

Answer 3

• Impetigo
• Mastitis
• Septicaemia
• Osteomyelitis

Question 4

Give some examples of toxin-mediated infections caused by Staph. aureus

Answer 4

• Scalded skin syndrome
• Pemphigus neonatorum
• Toxic shock syndrome
• Food poisoning

Question 5

What are enterotoxins?

Answer 5

An enterotoxin is a protein exotoxin released by a microorganism that targets the intestines

Question 6

What are Epidermolytic toxins

Answer 6

Cause blistering diseases

Question 7

What is Toxic Shock Syndrome?

Answer 7

• Causes toxic shock syndrome (multisystem and occasionally fatal).
• Associated with highly absorbent tampons.

Question 8

What are Haemolysins?

Answer 8

• Toxins
• Several types: α, b, gamma and delta
• Cytotoxic; cause lysis of red blood and other phagocytic and tissue cells.

Question 9

What is Panton-Valentine Leucocidin

Answer 9

• Destroys white blood cells – increases resistance to phagocytosis

Question 10

What is Hyaluronidase

Answer 10

Breaks down intracellular ground substance

(hyaluronic acid) of tissues

Question 11

How do bacteria resist antibiotics? ()

Answer 11

• Production of a penicillinase enzyme
• Mutation of essential penicillin binding protein found in bacterial cell envelope
• Glycopeptide resistance