Relapsing Bacillus cereus peritonitis in a patient treated with continuous ambulatory peritoneal dialysis

INTRODUCTION: Peritonitis is a severe complication of peritoneal dialysis (PD) due to associated morbidity and mortality. Although Bacillus cereus is mostly considered as a contaminant, its role as a causative agent in a few cases of PD peritonitis has been documented. Peritonitis due to B. cereus has been associated with high rates of catheter removal and resistance to beta-lactam antibiotics. CASE PRESENTATION: A case of relapsing peritonitis caused by B. cereus in a 69-year-old man with end-stage renal disease on continuous ambulatory PD for 3 years is described. B. cereus was recovered from the patient’s peritoneal fluid and was identified by phenotypic and molecular methods. The patient was treated, according to the susceptibility test, with tobramycin for 14 days. Cultures became sterile and the patient was discharged from hospital. Three days after discharge, the patient reported recurrence of abdominal pain and a new antibiotic regimen based on the previous culture results was initiated consisting of vancomycin and ciprofloxacin. The presence of B. cereus in the peritoneal fluid was confirmed, whereas repeated cultures for the next 15 days were positive. All B. cereus isolates produced biofilm. On day 16, the PD catheter was removed and the patient was transferred to haemodialysis. A review of previously reported cases is also presented. CONCLUSION: Since peritonitis is the most common cause of transition to haemodialysis, isolation of B. cereus from PD patients, even though rare, should not be considered as a contaminant. An appropriate antibiotic regimen and, whenever necessary, catheter removal should be applied.