Bacteraemic infection

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  • Created by: z
  • Created on: 04-03-16 19:24

Bacteraemia

septicaemia/bacteraemia is not a diagnosis- must think of pathway to blood e.g. 

  • catheter (trauma to urethral vessels)
  • IV or art lines
  • Ventilation
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Aetiology of bacteraemic infection

  • Precipitating agent, e.g. 
    • Endo toxin
    • Toxic shock syndrome toxin (S. aureus)
    • Erythrogenic toxin (group A strep)
    • cell wall of gram +ve bacteria
  • causes action in:
    • activation of complement
    • neutrophils, monocytes, cytokines (e.g. TNF, IL-1)
    • endothelial cells
  • which results in:
    • capillary leak (albumin may leave vessels, thus H2O follows > oedema, esp pulm)
    • fever
    • DIC
  • And ultimately
    • Shock (AKI= early sign)
    • Multiple organ failure 
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Signs associated with bacteraemia

  • Non blanching rash- DIC
  • Ischaemia of peripheries
  • Ascites
    • +/- Grey-Turner’s sign
      • In acute pancreatitis- bruising of flanks due to leakage of pancreatic secretions into paracolic gutters in 
    • +/- Cullen’s sign
      • Bruising around umbilicus
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Transient bacteraemia

  • Common after many events- not necessarily dangerous
    • 30-80% of dental extractions commonly Streptococci, diphtheroids, S. epidermidis
    • 40% of tonsillectomies – Streptococci, Haemophilus, diphtheroids
    • 15% of bronchoscopies – streptococci, S. epidermidids, aerobic gram –ve rods
    • 10% upper GI endoscopy – streptococci, s. epidermidis, diphtheroids, Neisseria
    • 2-10% colonoscopy – aerobic gram –ve rods, streptococci, Bacteroides
    • 10-36% urethral dilation – gram –ve rods, diphtheroids, streptococci
    • 5% partutition – aerobic gram –ve rods, streptococci
  • NB aerobic gram –ve bacilli=  Pseudomonas (aeruginosa), B. pertussis, legionella, E.coli (coliform), Klebsiella pneumoniae (coliform)
    • coliform= ferment lactose
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Bacteraemia: clinical

  • Presentation
    • Fever, rigors, shock 
    • Potentially w/ sympt from original source e.g. cough, sputum
  • Diagnosis
    • Isolate organisms form blood cultures
    • Take multiple samples- greatly incr chance of isolating causal organism
    • NB esp in infective endocarditis, many causes are also normal skin flora, thus difficult to differentiate b/w pathogen and contaminants from venepuncture
    • VITAL- fluorescence reduced if: decr O2, incr CO2 or decr pH= signs that bacteria present
  • Management
    • Reverse shock w/ IV fluids
    • IV high dose ab (broad spectrum if unknown)
    • NO role for corticosteroids
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Aetiology of clinically significant bacteraemia

  • E. coli: HA=CA – 29% 
  • S. aureus: HA >CA, 2:1 – 19% (ventilator)
  • S. pneumoniae: CA>HA, 10:1 – 13% (pneumonia)
  • Klebsiella: HA>CA, 3:1 – 7% (catheter/ventilator)
  • Pseudomona aeruginosa: HA>CA, 10:1
  • Viridans streptococci: CA>HA, 3:1
  • Coagulase-negative staphyloccic: HA>CA, 20:1 (IV lines in neutropenic pts)
  • Misc:19%
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Aetiology of infective endocarditis

  • Native valve (e.g. bicuspid valve/RHF)
    • A-haemolytic streptococci – 30%
    • S. aureus – 30% 
    • Enterococci – 10%
  • IVDU (normally easy to treat)
    • S. aureus – 55%
  • W/in 1 year of surgery (mainly SSIs)
    • Coagulase –ve staphylococci – 55% 
  • > 1 yr post-surgery (basically the same as native valve b/c becomes endothelised)
    • A-haemolytic streptococci – 30%
    • S. aureus – 15% 
    • Enterococci – 10%
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Symptoms of infective endocarditis

  • Fever – 90%
  • Malaise – 60%
  • Weight loss – 60%
  • Anorexia – 50%
  • Weakness – 50%
  • Sweats – 30%
  • Myalgia/arthralgia – 15%
  • Back pain – 10%
  • Confusion – 10%
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Signs of infective endocarditis

  • Pyrexia – 90%
  • Murmur – 85%
  • Embolic event – 35%
  • Splenomegaly – 25-50%
  • Stroke – 20%
  • Septic complications – 20%
  • Retinal lesion – <5% 
  • Peripheral signs
    • Petchiae – 25%
    • Osler’s nodes – 10%
    • Janeway lesions – 5-10%

NB FOU- if no history of travel, think IE

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Management of bacteraemia

  • Supportive therapy
    • Fluids (colloids, saline)
    • Inotropes (e.g .dobutamine w. monitoring)
    • Organ support (ventilation, haemofiltration)
  • Removal of infective focus
    • Abscess drainage
    • Removal of infected catheter
    • Wound debridement
  • Antibiotics
    • Initially IV and high dose
    • Broad spectrum if unknown aetiology and focus not able to remove e.g. cefotaxime + metronidazole in intra-abdominal sepsis, meropenem
    • Narrow spectrum if organism know e.g. fluclox for s.aureus
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