Decontamination of heater–cooler units associated with contamination by atypical mycobacteria

SummaryBackgroundNon-tuberculosis mycobacteria such as Mycobacterium chimaera are found widely in hospital water systems. Invasive M. chimaera infections have recently been attributed to heater–cooler units (HCUs) of cardiopulmonary bypass equipment.AimTo assess the extent of microbiological contamination within the HCUs and to inform decontamination strategies for reducing the microbial load.MethodsWater samples taken from HCUs used at University Hospitals Birmingham for cardiopulmonary bypass surgery were sampled to determine the number of micro-organisms by membrane filtration. Various decontamination processes were used throughout the study, all based on the manufacturer's guidance.FindingsTotal viable counts >300 cfu per 100 mL containing a wide variety of micro-organisms were obtained from water inside the HCUs. Working with the manufacturers, we significantly reduced the microbial load of the water within the HCUs by removing the internal tubing soiled with biofilm followed by a weekly decontamination regimen with peracetic acid.ConclusionA decontamination cycle including an initial replacement of internal tubing with weekly microbiological water samples is required to maintain the water quality within HCUs at an acceptable level.