Pyrexia/Sepsis Flashcards
How is fever defined?
Elevation of body temp >37C
Part of the systemic inflammatory response syndrome (SIRS)
What is the name of substances that cause fever?
Pyrogens
Give some examples of pyrogens
Endogenous - cytokines
Exogenous - Endotoxins from G-ve bacteria
What defines Pyrexia of Unknown Origin?
Temp > 38.3C
recorded on multiple occasions
present for at least three weeks
defied diagnosis after 3 days in hospital evaluation
What type of bacteria are staphylococci?
Gram-positive cocci that form grape-like clusters
In what types of patients is the rate of Staph Aureus colonisation higher?
Insulin-dependent diabetes, HIV infection, patients undergoing haemodialysis, individuals with skin damage.
What is the most frequent site of staph aureus colonisation?
Anterior narres (nostrils).
Also skin (damaged), vagina, axilla, perineum and oropharynx
How is sepsis defined?
Life-threatening organ dysfunction caused by disregulated host response to infection
How is septic shock identified?
Clinical construct of sepsis with persistent hypotension requiring vasopressors to maintain MAP >65 mmHg and serum lactate >2mmol/L
What are the criteria in qSOFA in sepsis and what is it used for?
- Hypotension Systolic BP <100mmHg
- Altered Mental Status
- Tachypnea RR >22/min
Score of >2 Criteria suggests greater risk of a poor outcome
What are the body’s defences against sepsis?
Physical barrier,
Innate immune system,
Adaptive immune system
List some commonly released bacterial toxins in sepsis?
Gram negative:
Lipopolysaccharide (LPS)
Gram positive:
Microbial-associated molecular pattern (MAMP)
-Lipoteichoic acid
-Muramyl dipeptides
Superantigens
- Staphylococcal toxic shock syndrome toxin (TSST)
- Streptococcal exotoxins
What bacterial toxin needs binding proteins to bind to macrophages?
LPS
What are the two types of mediators that can be released in sepsis?
- Pro-inflammatory mediators
- Compensatory anti-inflammatory mediators
What are the effects of excessive pro-inflammatory mediators?
- Promote endothelial cell – leukocyte adhesion
- Release of arachidonic acid metabolites
- Complement activation
- Vasodilatation of blood vessels by NO
- Increase coagulation by release of tissue factors and membrane coagulants
- Cause hyperthermia
What are the effects of excessive anti-inflammatory mediators?
- Inhibit TNF alpha
- Augment acute phase reaction
- Inhibit activation of coagulation system
- Provide negative feedback mechanisms to pro-inflammatory mediators
What do the pro-inflammatory mediators cause?
Sepsis -> Multiorgan failure -> Death
What do the compensatory anti-inflammatory mediators cause?
Immunoparalysis with uncontrolled infection -> Multiorgan failure
What do the clinical features of sepsis depend on?
- Host
- Organism
- Environment
What host factors may effect the presentation of sepsis?
- Age
- Co-morbidities
- Immunosuppression
- Previous surgery
What organism factors may effect the presentation of sepsis?
- Gram positive vs negative
- Virulence factors
- Bioburden
What environmental factors influence the presentation of sepsis?
- Occupation
- Travel
- Hospitalisation
Why would you take blood cultures in sepsis?
-To make a microbiological diagnosis (30-50% positive)
Why would you take lactate in sepsis?
-Marker of generalised hypoperfusion/severe sepsis/poorer prognosis
(Think lactate appearing in anaerobic respiration! Low oxygen!)
