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Updated: Jul 19, 2026

Microbiological Rapid On-Site Evaluation for Pulmonary Infectious Diseases
Published on: March 1, 2024
Pneumococcal pyomyositis: a patient with diagnostic problems and complications.
V T Baddour1, S T Hugenberg, K D Brandt
1Rheumatology Division, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
This case highlights Streptococcus pneumoniae pyomyositis, a rare infection mimicking connective tissue disease. Prompt diagnosis is crucial to prevent severe complications like osteomyelitis.
Area of Science:
- Infectious Diseases
- Rheumatology
- Radiology
Background:
- Pyomyositis is an uncommon intramuscular infection, often challenging to diagnose.
- This report details a case of Streptococcus pneumoniae pyomyositis in a patient with autoimmune markers but no overt connective tissue disease.
- The case involved iliacus, iliopsoas, and gluteus muscles.
Purpose of the Study:
- To report a unique case of Streptococcus pneumoniae pyomyositis.
- To emphasize the diagnostic challenges and potential mimics of connective tissue disease.
- To illustrate the rapid progression and potential complications of undiagnosed pyomyositis.
Main Methods:
- Case report of a patient with severe muscle pain and fever.
- Magnetic resonance imaging (MRI) to assess muscle involvement and disease progression.
- Laboratory investigations including autoimmune antibody titers.
Main Results:
- Streptococcus pneumoniae identified as the causative agent of pyomyositis.
- MRI revealed rapid progression from muscle edema to abscess formation within 10 days.
- Patient presented with elevated antinuclear and antiphospholipid antibodies without clinical connective tissue disease.
- Delayed diagnosis led to the development of osteomyelitis and sacroiliitis.
Conclusions:
- Pyomyositis should be considered in patients presenting with acute, severe, localized muscle pain and fever.
- Autoimmune markers may be present in pyomyositis without underlying connective tissue disease.
- Timely diagnosis and treatment of pyomyositis are essential to minimize morbidity and prevent complications.
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