An outbreak of bloodstream infections arising from hemodialysis equipment

An outbreak of 29 cases of bloodstream infection by 16 pathogens occurred during 8 months at two chronic hemodialysis centers. Consequences included 21 hospital admissions and removal of 23 dialysis catheters. An epidemiologic investigation comparing case-patients with uninfected controls showed that risk was significantly (P <.05) associated with having a catheter for vascular access; receiving treatment on a Monday, Wednesday, Friday schedule; and receiving treatment on one heavily contaminated dialysis machine. Culture studies and mock trials showed that bloodstream pathogens were present in a recently installed, commercially marketed attachment for disposal of spent priming saline and could enter blood line tubing directly or indirectly during dialyzer priming and tubing assembly. The outbreak was halted by measures directed at the attachment. Investigation of this problem demonstrated that microbial overgrowth in the attachment caused bloodstream infections and underscores the importance of microbiologic considerations in the design and use of hemodialysis equipment.