Peritonitis Due to Streptococcus uberis in a Patient on Automated Peritoneal Dialysis: A Case Report and Literature Review.

Peritoneal dialysis (PD)-related peritonitis remains a major cause of morbidity, technique failure, and hospitalization in patients receiving renal replacement therapy. While Staphylococcus species and Enterobacterales represent the predominant etiologies, emerging reports have described rare infections caused by environmental or zoonotic organisms. Streptococcus uberis, a bovine mastitis pathogen and ubiquitous environmental microorganism, has been only exceptionally associated with human disease. We report a case of peritonitis due to S. uberis in a 66-year-old male receiving automated peritoneal dialysis (APD; HomeChoice™ Pro Cycler, Baxter Healthcare, Deerfield, IL). The diagnosis was established using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS; Bruker Biotyper®, Bruker Daltonics, Bremen, Germany) and confirmed by sequencing of the sodA gene. Antimicrobial susceptibility testing (Etest®, bioMérieux, Marcy-l'Étoile, France) demonstrated susceptibility to β-lactams and glycopeptides. The patient was successfully treated with a 21-day course of intraperitoneal vancomycin and ceftazidime, with complete clinical resolution and no relapse at 18-month follow-up. This case expands the spectrum of pathogens implicated in PD-associated infections and highlights the role of advanced microbiological diagnostics in identifying uncommon organisms. Environmental exposure should be considered in PD patients presenting with atypical or culture-negative peritonitis.