Severe Streptococcus equi infection with bacteraemia, myositis and micro-abscesses in a 17-year-old healthy female following horse exposure

Abstract

Presentation
A 17-year-old healthy female presented with severe Streptococcus equi (S. equi) bacteraemia, left thigh myositis, micro-abscesses in the adductor minimus muscle and concomitant influenza B virus infection. She reported sporadic contact with horses.

Diagnosis
Was confirmed by positive blood culture, contrast-enhanced MRI of the left thigh, patient history, clinical findings, raised creatine kinase (CK), white blood cell (WBC) count, and C reactive protein (CRP).

Treatment
The patient received six weeks of intravenous (IV) Daptomycin, guided by blood culture and sensitivity report.

Discussion
S. equi is an uncommon zoonotic pathogen with diverse clinical manifestations. This case highlights the impact of transient immunosuppression, potentially induced by the influenza B virus infection, on the severity of S. equi infection. Furthermore, it emphasizes the importance of a thorough clinical history to prevent diagnostic delays and suboptimal outcomes.