Diagnostic challenge of Pasteurella multocida peritoneal dialysis—associated peritonitis in cirrhotic ascites: a case report

Pasteurella multocida is a recognized but uncommon cause of peritoneal dialysis-associated peritonitis, usually linked to household pet exposure. Concurrent cirrhotic ascites created initial diagnostic uncertainty, as concomitant spontaneous bacterial peritonitis could not be excluded at presentation. A man in his 80s with end-stage kidney disease on automated peritoneal dialysis and cirrhotic ascites presented with cloudy dialysate, abdominal bloating, near-syncope, hypotension, leukocytosis, and elevated lactate. Dialysis effluent contained 165 leukocytes/µL with 93% neutrophils; Gram stain showed gram-negative rods, and an outpatient effluent culture grew P. multocida susceptible to cefazolin. A household cat had been seen in the dialysis room, and possible tubing damage after dialysate was found on the floor was suspected, but no animal culture or strain comparison was performed. Native ascitic fluid was not obtained, so spontaneous bacterial peritonitis could not be definitively excluded. Therapy was narrowed to cefazolin, including once-daily intraperitoneal cefazolin administered with a prolonged dwell, for a 21-day course. He improved without catheter removal and remained asymptomatic at two-week and three-month follow-up. This case illustrates, rather than resolves, the diagnostic challenge of peritonitis in a patient with both peritoneal dialysis and cirrhotic ascites. Pet exposure should be assessed carefully, but suspected zoonotic transmission should be described cautiously when microbiologic confirmation from the animal is unavailable.