Bacillus cereus as a causative agent of peritonitis: A case report

Background: Bacillus cereus is a rare cause of bacterial peritonitis and mostly consideres as contamination if isolated from peritoneal cavity; however, as an opportunistic pathogen this gram negative bacilli can cause local and systemic infection in immunsuppressed individuals. Only few cases of isolated bacterial peritonitis with Bacillus cereus have been reported most of them were associated with peritoneal dialysis. Case Presentation: The patient is a 34 year old man, known case of End Stage Renal Disease, with history of drug addiction. He had history of kidney transplantation 10 years prior to admission which was rejected 2 years ago. Since then the patient was under hemodialysis 3 times weekly. He had also history of aortic valve replacement and mitral valve replacement surgery. Two weeks prior to this admission, the patient presented with dyspnea, orthopnea, nausea and vomiting which progressed to generalized abdominal pain, and distention of abdomen at time of admission. On physical examination the patient was agitated and tachycardic (HR: 110/min), (RR: 19/min). Blood pressure of 110/60mmHg was detected. He was afebrile. The abdomen was tender, with shifting dullness. Abdominal CT revealed only increased thickness of cecum. Patient’s drug history was positive for corticosteroid, and methadone. On hospital course ileal perforation was suspected for him and antibiotic therapy with metronidazole, and vancomycin was started. Abdominal tap from ascitic fluid was done and sent for pathology laboratory. Gram stain showed predominant population of large straight or slightly curved gram-positive bacilli with square ends singly or forming short chains . Centrally situated spores were observed in Malachite green staining. Also some gram negative bacilli were identified in gram stain. Culture of ascitic fluid showed irregular opaque colonies with rough surface surrounded by beta-hemolysis on blood agar, and positive motility which further diagnosed as bacillus cereus. Also ,Gram negative bacilli was an E-coli with ESBL resistant pattern. Conclusion:Isolation of Bacillus cereus from peritoneal fluid should not arbitrarily be considered as contamination, specially when isolated as single or dominant agent in immunocompromised patient. In these situations correlation with clinical findings can help to choose the best strategy and antibiotic regimen.

کلیدواژه ها:

Bacillus cereus ، peritoneal fluid ، Dialysis