Necrotizing fasciitis caused by Streptococcus pneumoniae in mixed connective tissue disease

A 42-year-old man was hospitalized because of chills, fever, and severe polyarthralgia. He had a 5-year history of mixed connective tissue disease (MCTD) with polyarthritis which had been treated with a nonsteroidal anti-inflammatory drug alone. On the second day of hospitalization, necrotizing fasciitis of the right leg developed. Streptococcus pneumoniae was later detected in a blood culture. Pneumococcal infections of the soft tissues are uncommon, and have been reported in immunosuppressed patients and patients with systemic lupus erythematosus. This is the first report of a case of necrotizing fasciitis caused by S. pneumoniae in a patient with MCTD.