Bacterial Pathogenesis Flashcards
Pathogenicity
The ability to cause disease in a susceptible host (plants, animals, humans)
Host Defenses
Beating First Line Defenses - Attachment
Attachment may be sufficient for disease
• Bordetella pertussis
– whooping cough
– Toxins produced
– No invasion
Beating First Line Defenses - - Invasion
Submucosa
- Local spread
- Bacteremia
- Metastatic spread
Beating Second Line Defenses
- Metabolism – nutrients, siderophores (Fe+++)
- Extracellular
– Phagocytes
– Complement
– Toll-like receptors (TLRs)
– molecular patterns (LPS)
– Adaptive immune system
- Intracellular – killing mechanisms of professional phagocytes
- Capsules
- Antiphagocytic
- Alternate pathway C3b – Serum factor H binding
Beating Second Line Defenses - Capsules
Beating Second Line Defenses - Adaptive Immunity
Beating Second Line Defenses - Extracellular Mechanisms
Beating Second Line Defenses - Phagosomal Replication
Beating Second Line Defenses - Resistance to Intracellular Killing
Beyond finding a site to replicate what is another benefit (for the pathogen) of an intracellular strategy?
Evade Th2 response
TH2 – is for extracellular (Antibodies/eosinophils) TH1 – is for intracellular (CD8 cytotoxic T-cells)
Injury
Toxins!
• Exotoxins
– A/B
– Pore-forming
– Superantigen
• Endotoxin Inflammatory Response
- Acute
- Chronic
A/B Toxins
Membrane Active Exotoxins
• Cytotoxins
– pore forming
– Inserts in lipid bilayer
– Leakage of essential components
– Osmotic instability
Superantigen Toxins
Protein (Toxin) Secretion
Endotoxin - LPS
Inflammation
Regulation
- Operons/regulons
- 2-component systems
Pathogenicity Island
