Pathogens and Hosts Flashcards
In what 7 ways can clinical infections be characterised?
Inflammation Pain Pyrexia Tachycardia Rigors Increased white cell count Increased C Reactive Protein
What are the 2 types of clinical infection?
Latent
Sub-clinical
Define a pathogen.
Organism which can cause disease.
Define commenal.
Organism which is part of the normal flora.
What are Koch’s postulates?
Four criteria that were established by Robert Koch to identify the causative agent of a particular disease.
What are the 4 Koch’s postulates?
Organism must be found in all cases of the disease
Be cultured outside the body
Reproudce the disease on inoculation
Define pathogenicity.
Capacity of a micro-organism to cause an infection.
Define infectivity.
Ability to become established.
Define virulence.
Ability to cause harmful effects once established.
Name the pathogen which would attach for infectivity.
E.Coli
Name the pathogen which would be acid resistant for infectivity.
Helicobacter pylori
What is virulence conferred by?
Virulence factors.
How do streptococcus pyogenes invade?
Necrotising fasciitis
Cellulitis
Connective tissue breakdown
Fibrinolysis
Define exotoxins.
Released extracellularly by the microorganism.
Define enterotoxins.
Exotoxins which act on the GI tract.
Define endotoxin.
Structurally part of the gram negative cell wall.
Name an exotoxin disease.
Clostridium Tetani
How does clostridium tetani cause death?
Respiratory paralysis.
How is clostridium tetani treated?
Debridement
Antibiotics
Antitoxin
Name an enterotoxin disease.
Cholera
How does cholera cause death?
Dehydration.
How is cholera treated?
Rehydration.
What are superantigens?
Certain exotoxins of strep pyogenes and staph aureus.
What do superantigens do?
Stimulate division of T cells in the absence of specific antigen, causing toxic shock from overwhelming cytokine production.
What part of the lipopolysaccharide is an endotoxin?
Lipid A
Name two types of endotoxin.
E.Coli
Neisseria meningitidis
What host responses are induced by endotoxins?
Cytokine production Fever Rigors Hypotension Tachycardia Collapse
