(624) Hyperammonemia Syndrome due to Ureaplasma Infection in an Infant With Neuroblastoma

Introduction: Non-hepatic hyperammonemia syndrome (NHHS) is a rare, but often fatal, cause of hyperammonemia. NHHS due to Ureaplasma species (spp). infection has been reported in previous literature and primarily occurs in patients with immunosuppression due to solid organ transplants, in particular lung transplants, and hematologic malignancies. Given the difficulty culturing Ureaplasma spp., it may be an underdiagnosed cause of encephalopathy in critically ill patients and may warrant surveillance in immunocompromised infants and children.

Description: An 8-month-old male with history of prematurity at 26 weeks gestational age, chronic lung disease, and grade II IVH, was admitted for an abdominal mass and abdominal compartment syndrome due to neuroblastoma. Chemotherapy was initiated with cyclophosphamide and topotecan. Despite starting filgrastim, he remained severely neutropenic after his first round of chemotherapy. On day 17 of admission the patient became febrile; blood cultures and a Karius test were sent, and antimicrobials were adjusted. Within 72 hours, he was noted to have an acute change in exam with nonreactive pupils, 4mm in diameter. Workup was significant for head CT consistent with severe HIE, severely elevated ammonia level (>2500 umol/L), and unremarkable urine organic acids and serum amino acids, ruling out inborn errors of metabolism as a source of hyperammonemia. Emergent measures to reduce intracranial pressure and ammonia were implemented, but brain MRI revealed global cerebral edema and tonsillar herniation. The family ultimately decided to withdraw support, and the patient died 2 days after the initial neurologic change. Karius testing would later result positive for Ureaplasma parvum.

Discussion: We present a unique case of an immunocompromised infant with neuroblastoma developing fatal NHHS due to Ureaplasma infection. Approximately 80% of pregnant women are colonized with Ureaplasma spp. with a risk for vertical transmission to neonates. Although it is of low virulence in adults, neonates may have a wide range of clinical manifestations from acute invasive infection to chronic inflammation. Early identification of Ureaplasma and initiating presumptive empiric antibiotic therapy may be warranted in at risk patients to prevent long-term neurologic damage or death.