(635) Severe Hyperammonemia Syndrome due to Ureaplasma urealyticum and Mycoplasma hominis Infection

Introduction: Hyperammonemia syndrome is a rare disorder with high mortality rates. In rare instances, it can be caused by congenital disorders and certain infections in immunocompromised hosts. We present a case of severe hyperammonemia syndrome with elevated methotrexate levels who presented acutely encephalopathic secondary to a Ureaplasma Urealyticum/Mycoplasma Hominis urinary tract infection.

Description: A 49-year-old-woman with past medical history of recurrent pyelonephritis, and granulomatosis with polyangiitis (GPA) on rituximab every 6 months, methotrexate weekly, and prednisone daily, presented with acute encephalopathy. The initial serum ammonia level was 1335 mcmol/L. Initial methotrexate level was elevated at 0.13 umol/L. Liver function tests and imaging were normal with no signs of cirrhosis. She was started on leucovorin and emergent continuous renal replacement (CRRT). Her extensive work up included a peripheral smear showing persistent tear drop cells, a bone marrow biopsy consistent with methotrexate toxicity, and a negative urea cycle disorder panel. MRI of the abdomen showed pyelonephritis and ureteritis. She progressed into acute hypoxic respiratory failure requiring intubation. Bronchoscopy with bronchoalveolar lavage (BAL) was performed. The patient’s blood cultures, urine cultures, and BAL grew Ureaplasma Urealyticum. Her BAL was also positive for Mycoplasma Hominis. She was treated with levofloxacin and doxycycline. The patient’s mental status and ammonia normalized; she was successfully extubated and liberated from CRRT. The patient was discharged to inpatient rehab facility after 32 days.

Discussion: Ureaplasma and Mycoplasma are rare and potentially fatal causes of hyperammonemia causing seizures, cerebral edema, and coma. Most seen in patients post lung transplantation. Both Ureaplasma and Mycoplasma are urease-producing organisms that can be associated with ureteritis. Prompt diagnosis with appropriate antibiotic administration is crucial. Typically, combination therapy should be utilized given these organisms propensity to be either initially resistant or develop resistance during therapy. This patient’s severe immunosuppression highlights the need to consider these organisms as possible causative agents even in those without transplant history.