Pathophysiology and Treatment of Sepsis Flashcards
Define sepsis.
Life-threatening organ dysfunction caused by a dysregulated host response to infection
Define septic shock.
A subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than sepsis alone
Describe the incidence of sepsis.
44,000 deaths in the UK
Globally: 20 million cases annually with mortality around 35% - second leading cause of death after vascular disease
How much does sepsis cost the NHS annually ?
Costs the NHS £2.5 billion per year
Where is sepsis generally acquired ?
Can be both community and hospital acquired
Describe the epidemiology of sepsis. Any populations at a greater risk ?
- Very young (< 1 year) and older adults (>75 years) or the very frail (although it affects all ages)
- Those with impaired immune system due to illness or medication (cancer, diabetes, spleen removed, rheumatic disease)
- Those who have had surgery/invasive procedure in last 6 weeks
- Anyone with breach of skin integrity (cuts, burns, blisters, skin infection
- People who misuse drugs intravenously
- People with indwelling lines or catheters
- Women who are pregnant, have given birth or had a termination of pregnancy or miscarriage in last 6 weeks
- Neonates
- Possibley a genetic factor
Describe the aetiology of sepsis.
• Vary significantly depending on region, hospital, season, type of unit • Pathogenic organisms identified in only around half of cases of sepsis • Source: (pretty much anything) – Respiratory Tract (around 60%) – Abdomen (26%) – Bloodstream (20%) – Skin (14%) – Urinary system (12%) – Unknown source (20-30%)
Identify some key causative pathogens of sepsis.
GRAM NEGATIVE SEPSIS (most common, 60%) • Enterobacteriaceae (e.g. E Coli, Klebsiella pneumoniae) • Pseudomonas aeruginosa • Neisseria meningitidis • Salmonella typhimurium
GRAM POSITIVE SEPSIS
• Staphylococcus aureus (including MRSA)
• Coagulase negative Staph, Enterococci and Streptococci (e.g. Strep Pneumonia, Strep pyogenes)
FUNGAL INFECTIONS
Candida
Which organisms are especially involved in post-splenectomy sepsis.
Encaspulated organisms
What barriers are breached in sepsis ?
Physical barriers (skin, mucous membranes, can also be more subtle like epithelial cell damage)
How may barriers be breached, in sepsis ?
– Catheters – Wounds – Burns – Thorn pricks – Insect bites
Identify the main factors affecting infection, in sepsis.
- Virulence of pathogen
- Bioburden
- Portal of entry
- Host susceptibility
- Temporal evolution
Explain how virulence of the pathogen affects infection in sepsis, using a specific pathogen as an example.
STREPTOCOCCUS PYOGENES
Before release of endotoxins:
• Cellulitis/impetigo
• Local pain
After release of endotoxins: • Cellulitis • Toxic shock • Hypotension • Altered mental state
Define bioburden, and explain how bioburden affects infection in sepsis, using a specific pathogen as an example.
Bioburden = Number of viable bacterial cells
SALMONELLA TYPHIMURUIUM
10^3 CFUs:
• Gurgling tummy
• Loose stools
10^5 CFUs:
• Haemorrhagic colitis
• Fever
• Abdominal pain
Explain how portal of entry affects infection in sepsis, using a specific pathogen as an example.
KLEBSIELLE PNEUMONIAE
Renal: • Tachycardia • Fever • UTI (may still end up with a chest infection)
Chest:
• Tachycardia
• Fever
• Hypotension
Explain how host susceptibility affects infection in sepsis, using a specific pathogen as an example.
STREPTOCOCCUS PNEUMONIAE
Fit Adult:
• Fever
• Pneumonia
Elderly (more comorbidities, possibly immunosupressed): • Fever • Pneumonia • Physical unsteadiness • Confusion • Altered mental state
State of nourishment (malnourished ?) can also affect state of the immune system (thereby making host more susceptible).