Bacterial pyomyositis in the United States.

The incidence of reported bacterial pyomyositis is increasing in the United States, especially among immunocompromised persons. This review summarizes all reported cases of pyomyositis among human immunodeficiency virus (HIV)-infected persons worldwide and HIV-negative persons in the United States since 1981. During the era of combination antiretroviral therapy, bacterial pyomyositis among HIV-infected persons typically occurred in those with end-stage acquired immunodeficiency syndrome. Among non-HIV-infected patients, about half have a serious underlying medical problem, most commonly diabetes mellitus, malignancy, or a rheumatologic condition. These patients are more likely to have a gram-negative infection, a normal white blood cell count, multifocal involvement, or higher mortality than those without an underlying medical condition. The characteristics of cases in temperate areas are similar to tropical cases, except that the former occurs more often in immunocompromised persons; this may change with the HIV epidemic in tropical regions.