Pediatric Guidance
Pyomyositis

Pyomyositis

Definition

An infection of a skeletal muscle caused by bacteria usually accompanied by abscess formation

Diagnosis

  • Acute onset of localized muscle pain with cramping usually in the lower limbs/gluteal muscles with fever >38.0°C +/- swelling and induration of the affected area
  • Other signs of systemic infection are usually present (e.g. tachycardia, leukocytosis)
  • Abscess can form within days / weeks
  • Signs of severe clinical progression (e.g. signs of sepsis/septic shock) should always be carefully monitored
  • Complications due to bacteremia can occur (e.g. septic emboli, septic arthritis, endocarditis)
  • Blood cultures (ideally before starting antibiotics)
  • Microscopy and culture of abscess fluid material (if this can be drained) to adjust empiric antibiotic treatment

Determine disease severity and help identify a bacterial infection: White blood cell count, C-reactive protein and/or procalcitonin

Initial X-ray is important to localize the site and extent of the infection and/or to exclude alternative diagnosis

  • Ultrasound is helpful to detect the presence of abscess (and to guide its drainage)
  • If available, also consider MRI or CT-scan because of their higher sensitivity to identify muscle swelling (i.e. inflammation) and the presence of purulent material

Microbiology

Treatment

  • Drainage of the abscess remains the main approach to eliminate the source of infection
  • Drainage is also important to obtain material for culture and identify the causative pathogen and its resistance profile
  • Mild: Targeted antibiotic treatment preferred after having obtained culture results
  • Severe or impossible to obtain a clinical sample for microbiological examination: Empiric treatment considering most likely pathogens including local prevalence and individual risk factors for MRSA

Important:

  • Simplify empiric treatment to a more narrow-spectrum antibiotic based on culture results or rapid clinical improvement if culture results unavailable
  • Step down to oral treatment is based on improvement of symptoms, signs of infection and the ability to take oral antibiotics

Additional Information

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