Staphylococcal pyomyositis in patients infected by the human immunodeficiency virus.

PURPOSE: We describe the manifestations of spontaneous staphylococcal pyomyositis in patients infected by the human immunodeficiency virus (HIV).

PATIENTS AND

METHODS

We present the courses of five previously unreported patients infected by HIV who presented to our medical centers with spontaneous staphylococcal pyomyositis. Additionally, we review all previously reported cases of this entity in HIV-infected patients and discuss its possible pathogenesis and importance in the context of HIV infection.

RESULTS

All patients presented with gradually developing fever and localized pain and swelling without accompanying leukocytosis. Often only scant evidence of local inflammation was found. None of our patients used intravenous drugs, had a history of trauma, had HIV- or zidovudine-related myositis, or had other conditions known to be associated with serious staphylococcal infections. Two patients studied had normal serum levels of all IgG subclasses. Elevated serum IgE, eosinophilic inflammatory infiltrates, or marked peripheral eosinophilia was observed in two patients.

CONCLUSIONS

Staphylococcal pyomyositis in HIV-infected patients presents in an indolent fashion, which may delay appropriate diagnosis and treatment. Since staphylococcal pyomyositis is infrequently reported in the United States, the development of 14 such cases (five in this series and nine previously reported) among the first 140,000 cases of acquired immunodeficiency syndrome in this country implies that this patient population is predisposed to this infectious complication. The pathogenesis of this entity is uncertain, but it is notable that HIV-infected patients are commonly colonized by Staphylococcus aureus and that neutrophils from HIV-infected patients frequently manifest phagocytic, chemotactic, and oxidative defects, diminished expression of Fc tau RIII (CD16) and CR1, and impaired bactericidal activity against S. aureus.