Marcello Montes Flashcards
(38 cards)
What is infective endocarditis
A life threatening infection of the heart valves or endocardium usually caused by bacteria entering the bloodstream and infecting the heart
What is bacteraemia
What are the durations (continuous, transient, intermittent)
The presence of bacteria in the blood, always abnormal as blood usually sterile. It is detected by blood culture
Continuous- persistent bacteraemia usually due to infected heart valve, blood infection, infected blood clot or blood vessel graft
Transient- bacteria in bloodstream from mins to hrs (15-30mins) typically harmless, can result from brushing teeth
Intermittent- periodic seeding of same bacteria in blood by existing infection elsewhere
What are the types of bacteraemia (primary, secondary)
Primary- the result of direct inoculation of bacteria into the bloodstream usually through IV drug use or contaminated venous catheter
Secondary- bacteria enters via alternative site such as cut in skin or mucous membrane, allowing microorganisms causing infection at another site to invade blood
What are some symptoms of infective endocarditis
Aching joints and muscles, chest pain, fatigue, flu like symptoms, night sweats, shortness of breath, swellings, heart murmur, weight loss, cutaneous manifestations, ocular changes (roths spots), splenomegaly, heart failure
What are the cutaneous manifestations of infective endocarditis (5)
Conjunctival petechiae: small red or purple spot on conjunctiva caused by minor bleed from broken capillaries
Mucosal petechiae: pinpoint haemorrhage in subcutaneous or submucosal tissue
Splinter haemorrhage: tiny blood clots running vertically under a nail caused by haemorrhage
Janeway lesion: non tender small erythematous or haemorrhagic lesion on palms or soles
Oslers node: tender purple pink nodules with pale centre generally found on distal fingers and toes as a result of immune complex formation in skin
What % of infective endocarditis have oral streptococci present
40%
What is sepsis
What is septicaemia
Sepsis- the putrefactive destruction of tissues by disease causing bacteria or their toxins, it is a life threatening reaction to an infection when the immune system overreacts and starts damaging own tissues and organs via inflammatory response
Septicaemia- a complication of sepsis, widespread tissue destruction due to presence presence of pathogenic microorganism or toxins in blood
What is SIRS
What is septic shock
SIRS - systemic inflammatory response syndrome, an inflammatory state affecting the whole body in response to infectious or non infectious insult
Septic shock- hypotension following an infection, sepsis often progresses to septic shock
Amber flag criteria of sepsis
10
- Relatives concerned about mental status
- acute deterioration in functional ability
- Immunosuppressed
- Trauma or surgery in past 6 weeks
- RR 21-24
- Systolic BP 91-100
- Heart rate 91-130 or new arrhythmia
- Not passed urine 12-18hrs
- Temp under 36 degrees
- Wound, device or skin infection
Red flag criteria of sepsis
10
- Unresponsive or responds only to voice or pain
- Systolic BP under 90
- Heart rate over 130bpm
- RR over 25
- Needs oxygen to keep SpO2 92%
- Non blanching rash
- Not passed urine 18hrs
- Urine output less than 0.5ml/kg/hr
- Lactate over 2 mmol/l
- Recent chemotherapy
What are the treatments for sepsis
3
Fluid replacement
IV Antibiotic combination therapy - usually broad spectrum (beta lactam) antibiotic + aminoglycoside or fluoroquinolone
Steroids
What are the criteria of SIRS
4
Temperature: >38 or <36
HR: over 90BPM
RR: >20 or PaCO2 <32
WBC count: >12,000 or <4,000
What is the criteria for sepsis
2
What is the criteria for severe sepsis
2
What is the criteria for septic shock
2
What is the criteria for MOF
2
SIRS + confirmed infection
Sepsis with evidence of organ dysfunction, hypo perfusion or hypotension
Sepsis + prolonged hypotension
Sepsis + irreversible organ failure
Theories of sepsis:
Gut hypothesis
Endotoxin macrophage hypothesis
Gut hypothesis: decreased gut blood flow and permeability lead to translocation of bacteria into the bloodstream
Endotoxin macrophage hypothesis: endotoxins released during infection cause release of pro inflammatory cytokines , thromboxane A2, prostacyclin, platelet activating factor and NO leading to whole body inflammation
Theories of sepsis:
Tissue hypoxia microvascular hypothesis
Mitochondrial DNA hypothesis
Integrated hypothesis
Tissue hypoxia microvascular hypothesis: insufficient supply of oxygen occurs after vascular changes leading to cell death and organ dysfunction
Mitochondrial DNA hypothesis: following cel death mitochondrial DNA leaks into bloodstream triggering neutrophil extracellular traps (NETs), this deadly immune response leads to MOF
Integrated hypothesis: sepsis caused by compromised homeostasis involving combination of mechanisms
Gram positive bacteria of sepsis
2
Gram negative bacteria of sepsis
3
Strep pneumoniae
Staph aureus
E coli
Klebsiella spp
Pseudomonas aeruginosa
What is the role of pathogen recognition receptors in sepsis
PRR recognise signals in the form of pathogen associated molecular patterns (PAMPs)
This causes activation of inflammation of inflammatory mediators and microvascular endothelium resulting in inflammation and thrombosis
This leads to occlusion of small blood vessels resulting in free radical production triggering ischaemia, tissue damage and MOF
What is the role of oxygen free radicals in sepsis
Immune cells, tissue hypoxia and cytokines produce oxygen free radicals
Oxygen free radicals cause mitochondrial dysfunction by decreasing capacity of ATP synthesis
What are the key pro inflammatory cytokines initiating SIRS response
2
What is the key pro inflammatory cytokine of sepsis
1
TNF alpha
IL 1
IL 6
What does endothelial cell damage in sepsis lead to
3
Vasodilation
Capillary leak
Leukocyte endothelial interactions
What is disseminated intravascular coagulation seen in sepsis
Blood clots form particularly in capillaries blocking vessels and reducing oxygen supply to organs and tissues
This can cause increased bleeding due to insufficient clotting factors left over
Symptoms include chest pain, shortness of breath, leg pain, problems speaking and moving
What is basic/fundamental research
What is applied research
What is clinical research
Basic/fundamental research is discovery research that increases knowledge of mechanisms of life or disease, it has no anticipated direct application
Applied research is directed towards development of treatment or drug
Clinical research tests drugs on humans in clinical trials
What is mathematical modelling and bioinformatics (in silico research)
Computer modelling- use of computers to study and simulate systems and behaviour using mathematical language
Bioinformatics- developing methods and software for understanding biological data
What are in vitro studies
What are in vivo studies
Studies performed in lab often using human cells and tissues - they do not involve model organism or animal
Lab studies involving animals
