Disinfection and cleaning of heater-cooler units: suspension- and biofilm-killing

Background: Non-tuberculous mycobacteria (NTM) infections in cardiac surgery patients, caused by Mycobacterium chimaera or Mycobacterium abscessus, have been traced to NTM-aerosols produced by heaterecooler units of cardiopulmonary bypass equipment. Aim: To develop a protocol to disinfect the water reservoir(s) of heaterecoolers to reduce NTM numbers and thereby prevent potential NTM aerosolization; and to devise an approach to disrupt surface biofilms of heaterecoolers to reduce reinoculation of the heaterecooler reservoir(s) after disinfection. Methods: A laboratory-scale Centers for Disease Control and Prevention bioreactor and a heaterecooler were inoculated with M. chimaera or M. abscessus to measure the ability of different disinfection protocols to reduce NTM colony-forming units in water and biofilm samples and to delay the reappearance of NTM after disinfection. Findings: The combination of an enzyme detergent cleaning agent and Clorox (R) were equivalent to Clorox alone in reducing M. chimaera cfu in heaterecooler water reservoir samples. However, reappearance of those bacteria was delayed by 12 weeks by the combination of enzyme detergent cleaning agent and Clorox exposure compared to Clorox disinfection alone. Conclusion: A combination of an enzyme detergent and Clorox was an effective disinfection treatment and significantly delayed the reappearance of M. chimaera in the heaterecooler reservoir. (C) 2020 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.