Toxins - Functions Flashcards
Exfoliatin toxin
Staphylococcal scalded skin syndrome
Produced by 5% of S. aureus
Absorbed into bloodstream and causes desquamation of skin
Acute exfoliation of skin following cellulitis
Act on desmosomes causing epidermal splitting
Toxic shock syndrome toxin
Causes toxic shock syndrome
20% of S. aureus produce it
8% mortality rate
Surgical would infections or super absorbant tampons
Fever, hypotension, multi-system shut down, organ failure, toxic shock
What does coagulase do?
Binds to fibrinogen on cell surfaces
This converts fibrinogen to fibrin
This produces fibrin clots
- Causes agglutination of bacterial cells
- Promotes bacterial attachment
- White cells penetrate fibrin clots poorly
What does catalase do
neutralises the production of oxygen free radicals in phagocytes
What does protein A do?
A surface protein
Binds IgG molecules by the Fc region
IgG is bound in he wrong orientation
This disrupts opsonisation and phagocytosis
What are invasins in staph
Degradative enzymes promote spread in tissues
Staphylokinase
Hyaluronidase
Thermostable deoxyribonuclease
What does staphylokinase do?
Dissolves fibrin clots laid down by during inflammation to try to wall of the infection
What does hyaluronidase do
Hydrolyses matrix of connective tissue
What does thermostable deoxyribonuclease do
Releases nutrients for organism
What does Panton-valentine leukocidan do
Produces pores in leukocytes - common in community-associated infection
What does haemolysin do
Produces pores in red blood cell
Staph food poisoning toxin
Produced by 30-50% of S. aureus strains
Heat stable (100 degrees for 10 minutes)
Resistant to gastric and jejunal enzyme
Ingestion cause vomiting, as it acts on the vagus nerve endings in the stomach) and diarrhoea (stimulate intestinal peristalsis)
What do pili do
They adhere to nonciliated mucosal epithelium
Antigenic variation - immune evasion
What does the Opa protein do
Assist in epithelium binding
Assist in antigenic variation and allow for immune evasion
What does iron binding protein do
Facilitates multiplication and colonisation
What does IgA protease do
This cleaves IgA1
Degrades host IgA
What does Por protein do
Forms pores
What does Lipooligosaccharide do
Causes tissue damage
Inhibits mucocillary clearance (nasal infections)
Immune evasion
Antigenic diversity
What do fimbriae do
Attach to nonciliated epithelial cells
Antigenic switching - allows for immune evasion
Bind ciliated epithelium
What does the capsule do
Prominent antiphagocytic polysaccharide
Immune evasion
What is iron acquisition for
Multiplication
What does haemagglutinin do
Attachment to epithelium
Pertussis toxin
Whooping cough
Lymphocytosis
Sensitisation to histamine
Activation of insulin producing causing hypoglycaemia
Dermonecrotic toxin
Vasoconstriction
Ischemic necrosis
