liver%20abscess
LIVER ABSCESS
Liver abscess may result from peritonitis and bowel leakage via portal circulation, direct spread from biliary disease or from hematogenous seeding.
Classical presentation includes fever, jaundice, and right upper quadrant symptoms (pain, guarding, rocking and rebound tenderness).
Biliary tract disease is the most common cause of bacterial liver abscess.
Most pyogenic liver abscesses are polymicrobial (eg enteric facultative and anaerobic species).

Principles of Therapy

Principles of Empiric Antibiotic Therapy

  • Antibiotics should be started as soon as pyogenic liver abscess is considered
  • Antibiotic therapy alone w/o drainage should be considered only in patients w/ small abscesses (<3-5 cm) that are not amenable to drainage & in those in whom drainage will pose an unreasonable risk
  • Initial antibiotics should be broad spectrum to cover common causative pathogens of pyogenic liver abscess
  • Metronidazole should be part of the initial therapy to provide empiric treatment for both anaerobes & E histolytica
  • Antibiotics should be based on local antimicrobial resistance patterns & modified based on culture & sensitivity testing results

Pharmacotherapy

Antibiotic Options

  • Ampicillin + Aminoglycoside
    • Should be part of antibiotic regimen when a biliary source is suspected
  • Cephalosporins
    • 2nd or 3rd generation cephalosporins are recommended when a colonic source is considered
    • Provide excellent coverage for enteric bacilli
    • Some cephalosporins have coverage against anaerobes
  • Metronidazole or Clindamycin
    • Should be included in antibiotic regimen to cover for anaerobes if other antibiotics being used do not have anaerobic coverage
    • If amoebiasis is suspected, Metronidazole should be started
  • Other antibiotics/antibiotic combinations that may be used for pyogenic liver abscesses include:
    • Antipseudomonal penicillins w/ or w/o beta-lactamase inhibitor
    • Carbapenems
      • Recommended for patients w/ diabetes mellitus (DM) due to risk of extended-spectrum beta-lactamase (ESBL) infection
    • Fluoroquinolone + Metronidazole +/- aminoglycoside
    • Vancomycin + Metronidazole +/- aminoglycoside

Drugs for Amoebic Liver Abscess

  • Chloroquine
    • May be used as an adjunct w/ Metronidazole in patients w/ large & multiple abscesses
    • Active against E histolytica trophozoites, achieves high concentrations in hepatic tissue
  • Metronidazole
    • Highly lethal to E histolytica trophozoites
    • Absorbed quickly through the gut w/ excellent bioavailability
  • Secnidazole, Tinidazole
    • May be substituted for Metronidazole in uncomplicated cases of invasive amoebiasis
  • Luminal amoebicides eg Diloxanide furoate, Etofamide, Iodoquinol, Nitazoxanide & Paromomycin are active against histolytica cysts & trophozoites in the intestine

Duration of Antibiotic Therapy

Pyogenic Liver Abscess

  • Duration of therapy should be based on severity of infection & patient’s response
  • Intravenous (IV) antibiotics should be continued for at least 2 weeks; therapy may be continued through the oral route afterwards for up to 6 weeks
  • Multiple abscesses may need up to 12 weeks of antibiotic treatment

Amoebic Abscess

  • Intravenous (IV) Metronidazole should be given for 5-10 days
  • Following a course of Metronidazole, an oral luminal amoebicide should be given for 7 days to eradicate residual amoeba in the intestines

Non-Pharmacological Therapy

Indications for Drainage

  • Most pyogenic abscesses require drainage
    • If multiple abscesses are present, only the largest abscess may require aspiration
    • Dispensing w/ a drainage procedure (ie giving antibiotics alone) should be considered only in patients w/ small abscesses not amenable to drainage or in those for whom drainage is too risky
  • Patients w/ amoebic abscesses require drainage only for very large lesions & for those in whom rupture is imminent

Percutaneous Needle Aspiration

  • Done under computed tomography (CT) scan or ultrasound guidance; often the initial diagnostic procedure performed for a single abscess ≤5 cm
  • Requires only local anesthesia & minimal sedation
  • Allows sampling of small &/or multiple lesions for culture; may do away w/ the need for catheter placement

Percutaneous Catheter Drainage

  • Standard of care for most liver abscesses
  • Entails placement of a catheter under ultrasound or computed tomography (CT) scan guidance followed by daily flushing
  • Should be the initial intervention for small abscesses <5 cm & for single abscess >5 cm
  • May be used for draining multiple abscesses
  • Advantages: Does not require general anesthesia, allows gradual drainage, faster recovery rate
  • Contraindications: Complicated thick-walled abscess w/ viscous pus, peritonitis, complicated access

Surgical Drainage

  • Indications for surgical drainage: Treatment of underlying intra-abdominal disorders including peritonitis, failure of previous percutaneous catheter drainage, multiple & loculated abscesses, ruptured abscess, viscous abscess obstructing the drain, large abscesses >5 cm
  • Open drainage may be through the transperitoneal or transpleural approach
  • Laparoscopic drainage enables exploration of entire abdomen w/ significantly reduced patient morbidity
  • Possible complications of drainage include recurrent pyogenic hepatic abscess, intra-abdominal abscess, kidney or liver failure, surgical wound infection

Endoscopic Retrograde Cholangiopancreatography (ERCP)

  • May be used in patients w/ prior biliary procedures & whose infection is connected w/ the biliary tree
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