Infectious DiseasesTier 2Disease (DEADMAN)

Abscesses

Description

An abscess is a localised collection of pus walled off by inflammatory tissue - the infectious diseases-specific focus is on site-appropriate organism coverage, source control, and recognising deep/complex abscesses (intra-abdominal, epidural, psoas) that require multidisciplinary management beyond simple incision and drainage

Epidemiology

Common across nearly every organ system; skin/soft tissue abscesses are the most frequent presentation, but deep-seated abscesses (intra-abdominal, epidural, hepatic, psoas) carry substantially higher morbidity if source control is delayed

Aetiopathogenesis

Pus formation reflects a localised, effective but contained innate immune response - the surrounding fibrous wall that makes an abscess drainable also limits antibiotic penetration into the cavity, explaining why source control (drainage) is mechanically necessary rather than optional in most cases

Diagnosis

Imaging (ultrasound, CT, or MRI depending on site) characterises location, size, and accessibility for drainage; blood cultures and abscess fluid culture guide organism-directed antibiotic therapy, particularly important for deep-seated collections where empirical cover may need broadening

Management

Source control (drainage - percutaneous image-guided or surgical) plus targeted antibiotics is the standard approach for any accessible abscess - antibiotics alone are frequently inadequate once a mature abscess has formed
Deep/complex abscesses (epidural, psoas, hepatic) require multidisciplinary input (surgery/interventional radiology plus infectious diseases) for both drainage planning and prolonged antimicrobial duration

Associations

Epidural abscess (neurosurgical emergency given cord compression risk), psoas abscess (may indicate underlying vertebral osteomyelitis or Crohn disease), hepatic abscess (amoebic vs pyogenic distinction relevant to travel history)

Natural history & complications

Antibiotics alone, without drainage, are frequently inadequate for a mature, walled-off abscess regardless of site - this is a fundamental principle that applies as much to deep intra-abdominal or epidural collections as to superficial skin abscesses

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