Metagenomic next-generation sequencing identifies Ureaplasma parvum in culture-negative peritoneal dialysis-associated peritonitis complicated by COVID-19: a case report.

Ureaplasma parvum is a fastidious, cell wall-deficient urogenital commensal that is rarely reported in peritoneal dialysis-associated peritonitis (PDAP) and often missed by routine culture. We describe a 43-year-old woman with stage 5 chronic kidney disease receiving maintenance peritoneal dialysis who presented with abdominal pain, diarrhea, fever, and cloudy effluent. The effluent nucleated cell count was 223/μL, with 85.3% neutrophils, and CT showed abdominopelvic fluid with mild irregular peritoneal thickening. Empirical broad-spectrum therapy failed, while repeated blood and effluent cultures remained negative. Metagenomic next-generation sequencing (mNGS) of peritoneal effluent identified U. parvum, confirmed by species-specific nucleic acid testing. Doxycycline therapy and catheter removal led to defervescence. Although coronavirus disease 2019 (COVID-19), inflammatory pulmonary changes, and colitis complicated the course, she recovered with targeted and supportive treatment. No recurrence occurred during 2 years of follow-up. However, because paired genital and intestinal specimens were not analyzed, the exact route of infection remains unconfirmed, which is a limitation of this study. CLINICAL TRIALS REGISTRATION: ChiCTR2600120155.