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Pyomyositis associated with Bacteroides fragilis in a patient with multiple myeloma
O Matsuno1, T Matsumoto, E Miyazaki
1Third Department of Internal Medicine, Oita Medical University, Hasama, Japan.
Abstract:
Pyomyositis is an infection of the skeletal muscle that is usually caused by Staphylococcus aureus. We report a 68-year-old Japanese woman who developed pyomyositis caused by Bacteroides fragilis following treatment for multiple myeloma. There are only two cases of pyomyositis associated with multiple myeloma in the literature. After receiving melphalan and prednisolone for five days, she developed multiple abscesses in the muscles of the right arm and thigh. Purulent exudate was aspirated from the abscess, and B. fragilis was identified. This is the first case of B. fragilis pyomyositis. Magnetic resonance imaging aided the diagnosis. Treatment consisted of surgical incision and drainage, with antibiotic administration. The immunosuppression caused by the myeloma and/or the chemotherapy presented a risk factor for the unusual infection observed in this patient.
Insights
This study reports a rare case of pyomyositis, a skeletal muscle infection, caused by Bacteroides fragilis in a multiple myeloma patient undergoing chemotherapy. This highlights an unusual bacterial cause of pyomyositis in immunocompromised individuals.
Area of Science:
- Infectious Diseases
- Oncology
- Microbiology
Background:
- Pyomyositis is typically a Staphylococcus aureus infection of skeletal muscle.
- Multiple myeloma is a cancer of plasma cells, often treated with chemotherapy that can cause immunosuppression.
Observation:
- A 68-year-old Japanese woman with multiple myeloma developed pyomyositis after melphalan and prednisolone treatment.
- Multiple abscesses formed in the muscles of her right arm and thigh.
Findings:
- Bacteroides fragilis, an unusual pathogen, was identified as the cause of pyomyositis.
- This is the first reported case of pyomyositis caused by Bacteroides fragilis.
- Magnetic resonance imaging (MRI) was crucial for diagnosing the abscesses.
Implications:
- The patient's immunosuppression from multiple myeloma and chemotherapy was a likely risk factor for this rare infection.
- This case expands the known spectrum of pathogens causing pyomyositis, particularly in immunocompromised patients.
- Prompt diagnosis and treatment involving surgical drainage and antibiotics are essential for managing pyomyositis.