Session 3 Flashcards
(34 cards)
Define sepsis.
A life threatening organ dysfunction due to a disregulated host response to infection.
Define septic shock.
Persisting hypotension due to sepsis.
Define bacteraemia.
Presence of bacteria in the blood.
What are some common symptoms of sepsis?
Fever, headache, nausea, weakness, generalised muscle aches, abdominal pain, photophobia, chills, non-specifically unwell, high resp rate, low BP, unresponsive.
How quickly should the Sepsis Six Bundle be completed?
Within an hour of presentation if sepsis is suspected.
What are the features of the Sepsis Six Bundle?
Give oxygen if needed, take blood cultures, IVAbx, fluid challenge, measure lactate levels, measure urine output.
Should also do FBC, U&E, EDTA (for PCR), BM, LFT, CRP, ABG, coat test and microbiology samples.
How do patients with meningitis typically present?
Symptoms of sepsis, widespread purpuric rash, neck stiffness.
What is the most common bacterial cause of sepsis?
Neisseria meningitidis.
What features of Neisseria meningitidis make it adapted to increase effectiveness?
Lipopolysaccharide endotoxins on cell surface trigger inflammation; pills enhance attachment to host cells; polysaccharide capsule around the cell promotes adherence and prevents phagocytosis.
Describe the inflammatory cascade.
- Cytokines are released and initiate thrombin production, promote coagulation and inhibit fibrinolysis
- Causes microvascular thrombosis resulting in organ ischaemia, dysfunction and failure
- Causes shock and multi-organ failure
How is a diagnosis of sepsis confirmed?
From blood cultures taken before antibiotic course started and PCR may be taken.
LP may be taken and the CSF may undergo microscopy, culture and PCR.
How is sepsis treated?
Antimicrobials: ceftriaxone usually used as effective against N. meningitidis.
Surgery: drainage, debridement or dead space removal.
Supportive treatments to relieve symptoms, restore patient physiologically.
Monitor/ assess regularly and consider ref to ITU
What are some complications of sepsis?
Irreversible hypotension, respiratory and renal failure, raised intercranial pressure leading to coning, ischaemic necrosis of the extremities.
What are the key features of the innate immune system?
Begins to act very rapidly, non-specific, no memory, doesn’t change in intensity.
What are the body’s innate barriers?
Physical barriers: skin, mucous membranes, bronchial cilia.
Physiological barriers: diarrhoea, vomiting, coughing, sneezing.
Chemical barriers: Low pH in stomach, vagina and on skin; antimicrobial molecules.
Biological barriers: normal body flora.
WHo is at high risk of infection from normal flora?
Asplenic and hyposplenic patients, patients with damaged or prosthetic valves, patients with PMH of infective endocarditis, immunocompromised patients.
What infections commonly result from antibiotic use?
Severe colitis of the intestine due to Clostridium difficile
Thrush of the vagina due to Candida albicans
What is the role of macrophages in innate immunity?
Ingest and destroy microbes via phagocytosis; produce cytokines/chemokines.
What is the role of monocytes in innate immunity?
Recruited to the infection site from the blood and differentiate into macrophages.
What is the role of neutrophils in innate immunity?
Recruited from the blood to sites of infection by chemokines, ingest and destroy progenitor bacteria (Staph. aureus and Strep. pyogenes).
What is the role of mast cells/basophils in innate immunity?
Cause inflammation early on (vasomodulation) and are important in allergic responses.
What is the role of eosinophils in innate immunity?
Defence against helminths.
What is the role of natural killer cells in innate immunity?
Kill all abnormal host cells; may be virally infected or malignant.
How are pathogens recognised by the innate immune system?
Using PAMPs on microbes: carbohydrate, lipid, protein and nucleic acid sequences recognised by phagocytes using PRRs.
Opsoninisation causes increased attachment of phagocytes and therefore increased clearance (essential to clear encapsulated bacteria).
