Bacteremia due to transplantation of contaminated cryopreserved pancreatic islets

OBJECTIVE: To report two cases of pancreatic islet transplantation-related septicemia, and the results of an investigative protocol to identify potential sources of contamination. DESIGN: Case series. SETTING: University hospital clinical investigational islet transplantation program. RESULTS: The last two of our first seven islet transplantation recipients developed Enterobacter cloacae septicemia within hours of islet infusion. Both had received thawed cryopreserved islet infusions. No source of infection apart from islets could be identified. Pancreas harvesting and islet isolation protocols provided multiple opportunities for contamination. Environmental cultures during a mock islet isolation procedure failed to identify a source of Enterobacter. Previously cryopreserved islet lots were thawed and submitted for culture, 14/47 grew micro-organisms including E. cloacae in four instances. Following revision of protocols for aseptic handling of islets during processing and cryopreservation 55 consecutive pancreata undergoing processing were evaluated; 7 grew micro-organisms on arrival and in 3 cases these persisted through to cryopreservation. CONCLUSION: Two of seven islet transplantation recipients developed septicemia, likely related to infusion of contaminated cryopreserved islets. Using existing technology, for isolating islets from donor pancreata, recipients will remain at risk for this complication. Prevention should entail strict adherence to aseptic technique, and, possibly, use of surveillance microbial cultures during the islet isolation process.