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

Abstract

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.

Keywords: Amoeba; Cardiac surgical procedures/instrumentation; Chlorine; Disinfection; Infection control; Mycobacterium chimaera.