Empiric antibiotic selection for primary pyomyositis in adults and children

This figure summarizes our approach to selecting initial empiric antibiotic therapy for treatment of primary pyomyositis in adults and children. Primary pyomyositis is a purulent infection of skeletal muscle, often with abscess formation. In patients with abscesses, percutaneous drainage is required in addition to antibiotic therapy. In the absence of an immunocompromising condition and/or signs of systemic infection/spesis, empiric coverage targets the most likely pathogens in primary pyomyositis, which are methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and group A Streptococcus. Patients with immunocompromising conditions and/or signs of systemic infection/spesis generally require broader initial empiric coverage. If a causative organism is identified, antibiotic therapy should be narrowed to target the pathogen, as appropriate. Once the patient has clinically improved and there is no residual abscess, the patient can be transitioned to oral therapy targeting the pathogen. Exceptions to this include patients with complications (eg, MSSA or MRSA bacteremia, septic arthritis, osteomyelitis) that require prolonged IV antibiotic therapy.

The guidance in this figure does not apply to patients with secondary pyomyositis (ie, caused by localized penetrating trauma or contiguous spread to the muscle), necrotizing fasciitis, or psoas abscess. Refer to separate UpToDate content for management of these conditions. This figure is intended for use in conjunction with other UpToDate content. For more information, refer to UpToDate's topic on primary pyomyositis.