Infections Flashcards
What is the definition of infection?
When pathogen overcomes body’s defences to cause tissue damage/dysfunction, leading to disease
When is a disease spread considered an epidemic?
When cases occur above normal/endemic rates (can be sudden or prolonged)
What is the difference between an outbreak and a pandemic?
Outbreak: epidemic but smaller area and more sudden
Pandemic: over wider area and affecting exceptionally high proportion of population
What is the difference between bacteraemia, septicaemia, and sepsis?
Bacteraemia → septicaemia → sepsis
Bacteraemia: presence of bacteria in bloodstream
Septicaemia: infection due to bacteraemia
Sepsis: symptoms resulting from septicaemia
What are some initial signs and eventual progressions of sepsis?
Initial: Fever, ↑HR, ↑RR
Progressed: MOF, uncontrolled BP/Septic shock
How can a person become immunocompromised?
Congenital/genetic
Age
Impaired bone marrow f(x) (via illness or treatment)
HIV infection
Co-infections
Co-morbidities
Major loss of normal barriers (eg. severe burns)
What are 3 general mechanisms of microbial pathogenesis?
1) Direct cell death/dysfunction
2) Local/systemic release of products (eg. bacterial exotoxins)
3) Induce immune responses that cause tissue dmg
What are 4 main patterns of bacterial infection?
1) Necrosis (exotoxin mediated)
2) Abscess formation (acute suppurative inflammatory rxn)
3) Chronic inflammatory responses (eg. granulomatous infection)
4) Endotoxic shock (only be G- organism)
How does endotoxic shock occur?
i) Bacterial lipopolysaccharide triggers host innate response
ii) Monocytes and macrophages release cytokines eg. TNF-alpha
iii) released cytokines act on endothelial cells
iv) in excess like in septicaemia, systemic vasodilation → hypotension → shock
What are 3 main patterns of viral infection?
1) Individual cell dysfunction/death (apoptosis and viral inclusions)
2) Viral transformation (eg. HPV→ enlarged nuclei + “halo”)
3) Latent viruses (eg. VZV)
What are the typical patterns of fungal infection?
Similar to bacterial infection but:
i) larger → ↑tissue dmg
ii) ↑ granulomatous rxns
iii) ↑ severe tissue necrosis
iv) invade and dmg vessels → ↑ thrombosis/haemorrhage
What is the characteristic feature of helminthic infections?
Eosinophilia in blood and tissues
