Inflammation of muscle, which may lead to pus formation and deep-seated muscle abscess.


  • Bacterial infection (commonly Staphylococcus aureus)

Clinical features

  • Most commonly localised in one muscle; usually large striated muscle
  • Fever, painful swelling of the involved muscle
  • Affected area is hot, swollen, and tender
  • Fluctuation when pus forms

Differential diagnosis

  • Cellulitis, boil
  • Osteomyelitis
  • Peritonitis (in pyomyositis of abdominal muscles)


  • Blood: Full blood count
  • Pus: culture and sensitivity
  • Consider HIV infection


  • Elevate and immobilise affected limb
  • Cloxacillin 500 mg IV or oral every 6 hours for 5-10 days Child: 12.5-25 mg/kg per dose
  • During the early stage, when the muscle is indurated, hot and swollen, antibiotic treatment
    may be sufficient to resolve the infection When abscess has formed,
  • Surgical drainage is the only effective treatment
    • Leave the wound open, pack and clean daily