Virulence Factors Flashcards
What is virulence?
The capacity of a microbe to cause damage to the host.
What is a virulence factor?
An intrinsic character of infectious bacteria that facilitates its ability to cause disease.
Name the 5 virulence factors
Adhesin Invasin Impedin Aggressin Modulin
Define an adhesin
Allows the organism to BIND to the host tissue
Define an invasin
Enables the organism to INVADE the host tissue
Define an impedin
Allows the organism to AVOID host defense mechanisms
Define an aggressin
Causes damage to the host DIRECTLY
Define a modulin
Causes damage to the host INDIRECTLY
Describe the pathogenicity of Staph aureus
- Superficial lesions leading to
- Systemic life-threatening infections
- Toxinoses
What are the main virulence factors of S. aureus?
- Adhesin: Fibrinogen Binding Protein
- Kills Leukocytes: Leukocidin (PVL)
- Causes shock, rash, desquamation: TSST-1 (toxin)
What is Panton-Valentine Leukocidin (PVL)
A bicomponent bacterial toxin with specific action against leukocytes
Name infections caused by S. aureus with PVL
- necrotising fasciitis
- necrotising pneumonia
- severe contagious skin infections
Which strains of S. aureus are more likely to contain PVL?
Infective CA-MRSA
Which strains of S. aureus are more likely to contain TSST-1?
All
Both colonising and infective HA-MRSA and CA-MRSA
Describe necrotising pneumonia
RAPID PROGRESSION from influenza-like syndrome Acute respiratory distress Refractory hypoxaemia Decreasing pulmonary function Multiorgan failure
