[Primary pyomyositis. Review of 32 cases diagnosed by ultrasound].

Primary pyomyositis is a bacterial infection of striated muscle which is acquired by hematogenous route. It is related to risk factors such as HIV/aids and other immuno suppressing diseases, and can be associated with local muscle stress factors. The most frequent etiology is Staphylococcus aureus. Its diagnostic delay may cause a fatal evolution. In this series 32 patients with primary pyomyositis diagnosed by ultrasound were evaluated. The most frequent risk factor was HIV/aids (61%). Local factors were detected in 21 (66%) cases: first, the practice of football. The monofocal form was observed in 19 (59%), the most commonly affected muscles were quadriceps, calves and psoas. Samples for bacteriological study were obtained in 30 cases, 22 blood culture and 27 abscess materials. In 30 cases the etiologic agent was isolated. Staphylococcus aureus accounted for 83.3% (25 cases) and Escherichia coli, Nocardia spp., Streptococcus agalactiae, nontuberculous mycobacteria, Pseudomonas aeruginosa were isolated in one case each. Seventeen patients received surgical treatment, aspirative punctures, 9; antibiotics alone, 4. Twenty eight (93.3%) patients had a good evolution; deaths, 2 (6.6%); unknown, 2. Main conclusions of this study were: due to the diverse and changing etiology of the primary pyomyositis it is important to recognize the etiological agent involved and their antibiotic susceptibility. The ultrasound performed the study in real time so it can be used to guide the puncture and to facilitate the immediate diagnosis. This makes the difference with other techniques and transforms it into a first-line method for the study of this disease.