Vermamoeba vermiformis resides in water-based heater-cooler units and can enhance Mycobacterium chimaera survival after chlorine exposure

Background: Mycobacterium chimaera colonizes water-based heater-cooler units (HCUs), from which it can spread to patients during surgery. Vermamoeba vermiformis is a free-living waterborne amoeba, which was consistently present within HCUs.Aim: To determine whether these amoebae can be involved in the persistent presence of M. chimaera.Methods: An in-vitro disinfection model.Findings: Increased survival of M. chimaera was observed after chlorine exposure in the presence of V. vermiformis. Confocal microscopy demonstrated the intracellular presence of M. chimaera in V. vermiformis.Conclusion: In this way, V. vermiformis can contribute to the persistent presence of M. chimaera in HCUs. Cleaning and disinfection protocols should take this phenomenon into account.(c) 2022 The Author(s). Published by Elsevier Ltd on behalf of The Healthcare Infection Society. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

The presence of V. vermiformis in water-based heater-cooler units can contribute to the persistent presence of M. chimaera. Cleaning and disinfection protocols should take this phenomenon into account.