Pyomyositis.

In the past, most cases of pyomyositis occurred among persons living in tropical climates, with the most common pathogen being Staphylococcus aureus. Increased numbers of cases have been reported more recently in North America, particularly in immunocompromised persons, such as those infected with the human immunodeficiency virus (HIV) and those with diabetes mellitus. These patients present with a wider variety of pathogens, including gram-negative bacteria, Streptococcus groups B, C and G, and Mycobacterium avium. Therefore, it seems prudent to consider pyomyositis in the differential diagnosis of persons with HIV infection, diabetes mellitus or other immunocompromising conditions, who present with persistent or worsening muscle aches and pains. Antibiotic treatment with a pencillinase-resistant penicillin is recommended for up to six weeks.