6.9. Skin and Soft Tissue Infection - Toxin Mediated Syndromes Flashcards
What causes Toxin Mediated Syndromes?
Superantigens, a group of Pyrogenic Exotoxins
How do Superantigens activate the immune system?
Not via the normal contact between Antigen Presenting Cell (APC) and T-Cells:
.1 Superantigens bypass APC, and attach directly onto the T-Cell Receptors, activating up to 20% of the pool, instead of the normal 0.01%
2. This causes a massive burst in Cytokine release
What does the massive burst in Cytokine release cause?
- Endothelial Leakage
- Haemodynamic Shock
- Multi-organ failure
- Death
What is the most common causative infectious agent of Toxin Mediated Syndromes?
- Strains of Staphylococcus Aureus:
- a) Toxic Shock Syndrome Toxin-1 (TSST-1)
- b) Endothelial A Receptor (ETA) and Endothelial B Receptor (ETB)
- Strains of Streptococcal Pyogenes:
- a) Toxic Shock Syndrome Toxin-1 (TSST-1)
What are the most common Toxin Mediated Syndromes?
- Staphylococcal Toxic Shock Syndrome
- Streptococcal Toxic Shock Syndrome
- Staphylococcal Scalded Skin Syndrome
- Panton-Valentine Leucocidin Toxin Syndrome
What is Toxic Shock Syndrome associated with?
- 1980’s - high absorbency tampons during menses
- Small skin infections due to Staphylococcus Aureus secreting Toxin Shock Syndrome Toxin -
1 (TSST-1)
What is the Diagnostic Criteria for Staphylococcal Toxic Shock Syndrome?
- Fever
- Hypotension
- Diffuse Macular Rash
- Three of the following organs involved: Liver, Blood, Renal, GI, CNS, Muscular
- Isolation of Staphylococcus Aureus from Mucosal / Normally Sterile Sites
- Production of TSST1 by isolate
- Development of antibody toxin during convalescence
What is Streptococcal Toxic Shock Syndrome associated with?
The presence of Streptococci in deep seating infections, such as:
1. Erysipelas
2. Necrotising Fasciitis
Is the Streptococcal Toxic Shock Syndrome mortality rate higher or lower than the Staphylococcal Toxic Shock Syndrome?
Streptococcal Toxic Shock Syndrome has a much higher mortality rate:
1. Streptococcal Toxic Shock Syndrome - 50%
2. Staphylococcal Toxic Shock Syndrome - 5%
What is the treatment of Toxic Shock Syndrome?
- Removal of offending agent (e.g. Tampon)
- I.V. Fluids
- Ionotropes
- Antibiotics
- I.V. Immunoglobulins
- Urgens Surgical Debridement of the infected Tissue (Strep. TSS)
What is Staphylococcal Scalded Skin Syndrome infection due to?
A particular strain of Staphylococcus Aureus which produces:
1. Exfoliative Toxin A
2. Exfoliative Toxin B
How is Staphylococcal Scalded Skin Syndrome characterised?
- Widespread Bullae
- Skin Exfoliation
Which group of people is Staphylococcal Scalded Skin Syndrome most commonly found?
Children
Note - it can occur in adults as well
What is the treatment of Staphylococcal Scalded Skin Syndrome?
- I.V. Fluids
- I.V. Antimicrobials
What is the mortality rate of Staphylococcal Scalded Skin Syndrome?
3% in children
Higher in adults who are often immunocompromised