A Unique Case Linking Rituximab to a Ureaplasma Infection and Life-Threatening Hyperammonemia

Rituximab is an anti-CD20 monoclonal antibody medication used in treating various cancers like non-Hodgkin lymphomas as well as immunologic conditions like granulomatosis with polyangiitis. It disrupts and decreases the number of B-cells, which causes an immunosuppressive state. This can promote the growth of numerous rare and opportunistic pathogens, one of which is <i>Ureaplasma</i>. Increasing cases of <i>Ureaplasma</i> infections have been reported with rituximab use, but they do not typically present with hyperammonemia. This is a case of widespread <i>Ureaplasma urealyticum</i> infection with shock, polyarticular arthritis and life-threatening hyperammonemia (ammonia levels greater than 160 microlmol/L) after rituximab use for granulomatosis with polyangiitis. It draws attention to the crucial point that early recognition of symptoms and timely diagnosis can lead to improved patient outcomes. Ureaplasma and other opportunistic organisms must be considered when reviewing patients on immunomodulating therapy.