A case of Kocuria rhizophila infection and persistence in ascitic fluid of a peritoneal dialysis patient with polycystic kidney disease.

Peritoneal dialysis (PD) is a well-established renal replacement therapy for patients with end-stage renal disease, but peritonitis continues to represent a significant clinical challenge. While most cases are attributed to gram-positive bacteria from the skin microbiota, emerging reports have documented infections with atypical organisms, including Kocuria species. Here we present the case of a 68-year-old woman with autosomal dominant polycystic kidney disease on peritoneal dialysis who developed recurrent peritonitis episodes due to Kocuria rhizophila, a microorganism traditionally considered a non-pathogenic commensal. Despite initial resolution following intraperitoneal vancomycin therapy, the patient experienced multiple relapses within short intervals, raising concerns regarding biofilm formation and antibiotic resistance. This report highlights the diagnostic complexities, therapeutic uncertainties, and the need for accurate microbiological identification in managing uncommon pathogens. It also underscores the importance of tailored strategies and vigilant monitoring in recurrent PD-related peritonitis.