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

Abstract

Non-tuberculous mycobacteria (NTM) infections in cardiac surgery patients, caused by Mycobacterium chimaera or Mycobacterium abscessus, have been traced to NTM-aerosols produced by heater-cooler units of cardiopulmonary bypass equipment. To develop a protocol to disinfect the water reservoir(s) of heater-coolers to reduce NTM numbers and thereby prevent potential NTM aerosolization; and to devise an approach to disrupt surface biofilms of heater-coolers to reduce reinoculation of the heater-cooler reservoir(s) after disinfection. A laboratory-scale Centers for Disease Control and Prevention bioreactor and a heater-cooler 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. The combination of an enzyme detergent cleaning agent and Clorox® were equivalent to Clorox alone in reducing M. chimaera cfu in heater-cooler 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. A combination of an enzyme detergent and Clorox was an effective disinfection treatment and significantly delayed the reappearance of M. chimaera in the heater-cooler reservoir.