First report of septicemia caused by an obligately anaerobic Staphylococcus aureus infection in a human.

In this case report, we describe the first instance of septicemia caused by an obligately anaerobic Staphylococcus aureus in a human. A 45-year-old man presented with septicemia, septic arthritis, and multiple pulmonary abscesses, which were caused by an obligately anaerobic S. aureus. The clinical and microbiological features that led to the diagnosis are discussed. Genotyping cannot at present reliably separate S. aureus subsp. aureus from S. aureus subsp. anaerobius, but phenotypic characteristics suggest that the present isolate is a previously undescribed strain of anaerobic Staphylococcus aureus.