A rare case of peritoneal dialysis-associated peritonitis caused by Coxiella burnetii diagnosed by mNGS.

We report a rare case of peritoneal dialysis (PD)-associated peritonitis caused by Coxiella burnetii, an intracellular pathogen typically associated with Q fever. A 28-year-old female with lupus nephritis and end-stage kidney disease on PD presented with cloudy effluent and abdominal pain after consuming undercooked lamb. Despite initial empirical broad-spectrum antibiotic therapy (cefazolin/ceftazidime protocol), clinical symptoms persisted. Conventional bacterial, fungal, and mycobacterial cultures were negative. Metagenomic next-generation sequencing (mNGS) of the peritoneal effluent identified C. burnetii DNA. The treatment was transitioned to doxycycline and hydroxychloroquine resulted in clinical improvement and normalization of inflammatory markers. This case underscores the diagnostic value of mNGS in culture-negative peritonitis and emphasizes C. burnetii as an emerging pathogen in immunocompromised PD patients, particularly with zoonotic exposure histories.