Pyomyositis in patients with the human immunodeficiency virus: an unusual form of disseminated bacterial infection

PURPOSE AND PATIENTS: Pyomyositis, a common disease in the tropics, is rare in the continental United States, with approximately 83 cases described in the literature in the past two decades. The occurrence of pyomyositis complicating human immunodeficiency virus (HIV) infection has been reported in 10 patients since 1986. We report six cases of this entity in patients with advanced HIV disease seen in our institution over a 20-month period. A common denominator in all of our patients was muscle injury, induced by either exercise or trauma. Unlike most previous reports of HIV-associated pyomyositis, the clinical picture in our cases was complicated by the development of abscesses in multiple muscle groups, requiring prolonged antimicrobial therapy and repeated drainage procedures for successful management. Interestingly, one patient developed concomitant rhabdomyolysis--an otherwise rare event in classical pyomyositis. Staphylococcus aureus was the predominant infecting organism in this as well as all other series. Of note, we also observed and report the first case, to our knowledge, of gram-negative pyomyositis in an HIV-infected individual. The pathogenic implications of this catalase-producing gram-negative isolate are discussed in the context of neutrophil abnormalities in HIV disease. CONCLUSION: Like tropical pyomyositis, its HIV-associated counterpart appears to be multifactorial in origin. Its recent recognition suggests that, in addition to underlying abnormalities of host defense, factors relating to the prolonged survival of patients with late-stage disease, including myopathy, might play an important contributory role.