[Primary pyomyositis caused by Streptococcus intermedius]

Pyomyositis is a sub-acute bacterial infection that affects the striated muscle and is usually accompanied by the formation of an abscess in this muscle. It was initially described as an endemic disease in the tropics and only in recent years has an increase been observed in the number of cases in countries with a temperate climate in relation to an increase of immuno-depressed patients. The causal germ is Staphylococcus aureus in more than 75% of cases. The most useful imaging test is magnetic resonance. Treatment consists of complete surgical draining of the abscess combined with a suitable antibiotic therapy. We present a case of primary pyomyositis of the quadriceps in a diabetic patient with a remote traumatic antecedent of the affected zone and caused by an unusual germ. A complete recovery was obtained, without sequels, following surgical draining and 4 weeks of endovenous antibiotic treatment.