Ureaplasma septic arthritis in an immunosuppressed patient with juvenile idiopathic arthritis.

Mycoplasmas, including Ureaplasma and Mycoplasma species, are uncommon but important causes of septic arthritis, especially affecting immunosuppressed patients. Many of the reported cases have been associated with congenital immunodeficiency disorders, especially hypogammaglobulinemia. Mycoplasmas are difficult to grow in the laboratory, and these infections may be underdiagnosed using culture techniques. We report a case of a 21-year-old woman with juvenile idiopathic arthritis and hip arthroplasties treated with rituximab and adalimumab who developed urogenital infections and soft tissue abscesses followed by knee arthritis with negative routine cultures. Ureaplasma species was identified from synovial fluid on 2 separate occasions using a broad-range 16S ribosomal RNA gene polymerase chain reaction. Azithromycin led to rapid improvement in symptoms, but after completion of therapy, involvement of the hip prosthesis became apparent, and again, 16S rRNA gene polymerase chain reaction was positive for Ureaplasma species. The literature is reviewed with a discussion of risk factors for Mycoplasma septic arthritis, clinical presentation, methods of diagnosis, and treatment.