Primary erector spinae pyomyositis causing an epidural abscess: case report and literature review.

Background Context: Primary pyomyositis (PM) is a rare bacterial infection of skeletal muscle usually restricted to tropical zones. Typically caused by Staphylococcus aureus, primary staphylococcal PM associated with an epidural abscess has not been reported before.

Purpose: We present the first case of staphylococcal PM associated with an epidural abscess.

Study Design: Case report.

Patient Sample: A 56-year-old woman.

Outcome Measures: Clinical follow-up at 9 months.

Methods: This 56-year-old woman presented with a sudden onset of left lumbar back pain and sciatica without prior illness. She was pyrexial on admission, with elevated inflammatory markers but with no obvious systemic source of sepsis.

Results: Spinal magnetic resonance imaging and subsequent surgery revealed an erector spinae abscess causing an epidural abscess via the left L4/5 intervertebral foramen. Both back pain and sciatica were immediately improved postoperatively. Culture revealed S aureus as the sole organism sensitive to flucloxacillin. Intravenous therapy was converted to oral after 12 days once the erythrocyte sedimentation rate had normalized and she was asymptomatic. She remains asymptomatic and without clinical signs at the 9-month follow-up.

Conclusion: Spinal infection must always be considered when back pain and sciatica are associated with clinical signs of sepsis. We present the first case of staphylococcal PM associated with an epidural abscess.