From the Guidelines
Secondary pyomyositis should be treated with prompt administration of antibiotics, typically starting with empiric therapy using vancomycin, and early drainage of purulent material, as recommended by the Infectious Diseases Society of America 1.
Diagnosis and Treatment
The diagnosis of secondary pyomyositis requires imaging, with MRI being the most sensitive modality, and aspiration for culture 1. The most common causative organism is Staphylococcus aureus, including MRSA. Patients typically present with fever, muscle pain, and swelling.
Antibiotic Therapy
Antibiotic therapy should be adjusted based on culture results, with a total duration of 2-4 weeks for uncomplicated cases and 4-6 weeks for complicated cases. Vancomycin is recommended for initial empirical therapy, with the addition of an agent active against enteric gram-negative bacilli for infection in immunocompromised patients or following open trauma to the muscles 1.
Surgical Drainage
Surgical drainage is necessary for abscesses larger than 3cm, and early drainage of purulent material should be performed to prevent morbidity and mortality 1.
Risk Factors and Complications
Risk factors for secondary pyomyositis include diabetes, HIV, malignancy, and immunosuppression. Complications can include compartment syndrome, septic shock, and metastatic infections, so early diagnosis and aggressive treatment are essential to prevent morbidity and mortality.
Key Recommendations
- MRI is the recommended imaging modality for establishing the diagnosis of pyomyositis 1.
- Cultures of blood and abscess material should be obtained 1.
- Vancomycin is recommended for initial empirical therapy, with the addition of an agent active against enteric gram-negative bacilli for infection in immunocompromised patients or following open trauma to the muscles 1.
- Early drainage of purulent material should be performed 1.
From the Research
Definition and Causes of Secondary Pyomyositis
- Secondary pyomyositis is a serious, life-threatening complication of an underlying infection, often occurring in association with pelvic and lumbo-sacral infections 2.
- The condition is characterized by a pyogenic infection of the muscle, which can lead to abscess formation 3.
- Various bacteria can cause secondary pyomyositis, including Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus anginosus 4, 2, 5.
Clinical Presentation and Diagnosis
- Patients with secondary pyomyositis often present with muscle pain, fever, and swelling, which can mimic other conditions such as septic arthritis or appendicitis 4, 2.
- Imaging methods like ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) are essential for diagnosing secondary pyomyositis 2.
- Laboratory tests, including markers of inflammation like C-reactive protein and erythrocyte sedimentation rate, can help assess the intensity of inflammation 2.
Treatment and Management
- Early recognition and aggressive management with antibiotics, incision, and drainage are crucial for reducing morbidity and mortality in secondary pyomyositis 2, 6.
- The treatment approach depends on the stage of the disease, with stage 1 pyomyositis (muscle edema) treated conservatively with antibiotics, and stage 2 and 3 pyomyositis requiring surgical intervention with abscess aspiration and drainage 2.
- Open and percutaneous drainage procedures are commonly used in the management of secondary pyomyositis, with approximately half of all patients receiving more than one class of antibiotic 3.