A 16-Year-Old with a Mycoplasma hominis Empyema Post-Lung Transplantation: A Case Report

This is the first reported case of empyema due to Mycoplasma hominis in a pediatric transplant recipient.

A 16-year-old Indigenous Canadian boy developed acute respiratory distress 29 days post-bilateral lung transplantation for chronic lung disease and pulmonary hypertension secondary to extreme prematurity and an atrial septal defect. Pre-transplant donor bronchial cultures grew Candida albicans and methicillin-sensitive Staphylococcus aureus, so he received 14 days of cefazolin. Post-transplant prophylaxis included azithromycin, voriconazole, micafungin, TMP-SMX, and valacyclovir. Immunosuppression included anti-thymocyte globulin induction, followed by tacrolimus, mycophenolate mofetil, and prednisone. The patient developed a large right pleural effusion over the course of 24 h requiring intensive care and high-flow supplemental oxygen. Pleural thoracentesis revealed a neutrophil-predominant exudative empyema. Routine cultures were negative; M. hominis was detected by PCR and specialized media. The patient completed 28 days of clindamycin and doxycycline and made an uneventful recovery.

M. hominis and Ureaplasma species are donor-derived pathogens that can cause significant morbidity, including sternal wound infection, mediastinitis, pericarditis, and empyema. Post-lung transplant M. hominis infections occur in 2%-5% of cases. Diagnostic challenges, low clinical suspicion, and rising resistance contribute to poor outcomes and inappropriate antibiotic use. Although this patient's ammonia level was normal, hyperammonemia syndrome also remains a rare but serious complication of Ureaplasma urealyticum and M. hominis infections.

Early screening, PCR testing, and prompt combination empiric therapy are crucial for improving outcomes in M. hominis infections.