Ureaplasma urealyticum septic arthritis in hypogammaglobulinemia

We describe a hypogammaglobulinemic man with erosive oligoarticular septic arthritis due to Ureaplasma urealyticum. His clinical course was complicated by a subcutaneous abscess. Multiple synovial cultures were negative until finally cultures specific for mycoplasmas were performed. Serologic diagnosis cannot be relied upon in hypogammaglobulinemic patients because they do not mount a perceptible antibody response. This underscores the importance of a high clinical suspicion of mycoplasmas as etiologic agents of septic arthritis in this population and early communication with the microbiology laboratory so that appropriate cultures for mycoplasmas can be performed and joint destruction minimized.