How do Staphylococcus and Streptococcus bacteria cause myositis?

Staphylococcus and Streptococcus bacteria cause myositis primarily through two mechanisms: direct invasion of muscle tissue or the production of toxins that poison the tissue.1

While muscle tissue is generally highly resistant to bacterial invasion, physical injury can weaken local defense mechanisms, creating an environment that facilitates infection. Once established, the infection triggers an inflammatory response characterized by local pain, swelling, and warmth, often accompanied by systemic symptoms such as fever, chills, and headaches.12

As the condition progresses, the tissue may be infiltrated by white blood cells and lymph cells, potentially leading to the formation of pustulant abscesses. In most cases, bacterial myositis is localized and typically responds to treatment with antibiotics and, if necessary, minor surgical intervention.12