First successful use of Ampicillin-Sulbactam for rare Streptococcus agalactiae-associated peritonitis in peritoneal dialysis: A case report and literature review

Carlos Berrocal¹J M Quintero-Romero¹Luz Mejia¹A Zapata-Aristizábal²Humberto Alejandro Nati Castillo³Alice Gaibor-Pazmiño⁴Juan S. Izquierdo-Condoy^5*

• ¹Universidad del Valle, Cali, Colombia
• ²Corporacion Universitaria Empresarial Alexander Von Humboldt, Armenia, Colombia
• ³Universidad Libre - Campus Cali, Cali, Colombia
• ⁴Universidad de Las Americas, Quito, Ecuador
• ⁵University of the Americas, Quito, Ecuador

Introduction: Peritonitis is a major complication of peritoneal dialysis, most often caused by gram-positive cocci. Streptococcus agalactiae (Group B Streptococcus) is an exceptionally rare pathogen in this context. Case presentation: We describe a 64-year-old man with end-stage renal disease on long-term PD who developed refractory peritonitis due to S. agalactiae. Peritoneal fluid analysis revealed 525 leukocytes/μL (74% polymorphonuclear cells) and Gram-positive cocci. Cultures confirmed S. agalactiae, fully susceptible to all tested antibiotics. Despite intraperitoneal vancomycin, the patient showed no clinical improvement. Because of limited intraperitoneal antibiotic availability, intravenous ampicillin–sulbactam (1.5 g every 12 hours) was initiated, combined with prophylactic oral fluconazole. Clinical resolution was achieved after 10 days, followed by four days of oral therapy. The peritoneal catheter was subsequently removed, and the patient transitioned to intermittent hemodialysis. Conclusions: This case represents the first documented success of intravenous ampicillin–sulbactam for S. agalactiae–associated peritonitis in PD. It expands the therapeutic options for this rare and challenging infection and highlights the importance of culture-guided management and adaptive treatment strategies, particularly in resource-limited settings where conventional intraperitoneal therapies may be unavailable.