Progressive bacterial synergistic gangrene is a mixed bacterial infection typically involving microaerophilic streptococci and Staphylococcus aureus. It occurs postoperatively at abdominal and thoracic surgery sites. It is a mixed bacterial infection of Streptococcus, typically found at the margins of the wound, and S aureus or Enterobacteriaceae species, found at the center.

This infection almost always begins at an abdominal or thoracic surgery wound site, beginning a few days to a few weeks after surgery. There is severe pain, but remarkably there is little systemic toxicity.