infection control & hospital epidemiology october 2017, vol. 38, no. 10 concise communication


Decontamination of an Extracorporeal Membrane Oxygenator Contaminated With Mycobacterium chimaera


Mark I. Garvey, PhD, MSc, BSc, DipHIC; Natalie Phillips, BSs, PGDip, ACP; Craig W. Bradley, RN, BSc; Elisabeth Holden, FRCPath


Water samples taken from extracorporeal membrane oxygenator (ECMO) devices used at University Hospitals Birmingham yielded high total viable counts (TVCs) containing a variety of microorgan- isms, including M. chimaera. Disinfection resulted in the reduction of TVCs and eradication of Mycobacterium chimaera. Weekly disinfec- tion and water sampling are required to manage the water quality in these devices.


Infect Control Hosp Epidemiol 2017;38:1244–1246


Over the past 2 years, several reports have detailed cases of sterile site infection caused by Mycobacteriumchimaera among postoperative cardiac surgery patients.1–3 Such infections have been associated with contaminated heater-cooler units (HCUs) used in operating rooms. Transmission of infection is thought to occur via aerosolization of contaminated water from these devices.4–6 Mycobacterium chimaera is a slow-growing nontuberculous


mycobacterium (NTM) belonging to the M. avium complex (MAC) (M. avium and M. intracellulare).1,2 Mycobacerium chimaera may cause pulmonary infection, especially in patients with underlying respiratory disease, as well as skin and bone infection, and disseminated infection in the immunocom- promised.4,5 As an environmental organism, M. chimaera has been identified in biofilms and water sources, including household water.4,5 Nontuberculous mycobacteria are also recognized biofilm-forming constituents of hospital water systems that have the potential to infect patients, primarily via an aerosol route.1–6 Public Health England (PHE) guidelines published last


month highlight the use of extracorporeal membrane oxyge- nation (ECMO) devices as a risk factor for M. chimaera infection.7 It has been hypothesized that ECMO treatment might constitute a risk for transmission of water-borne pathogens,8 and ECMO is a life-saving technology, particu- larly for patients with severe respiratory failure.8 Additionally, venoarterial circuit configurations offer prolonged circulatory support, which is comparable to the short-term support pro- vided by cardiopulmonary bypass during cardiac surgery.8 While patients treated with ECMO for respiratory failure have smaller potential entry sites for pathogens than those


undergoing open-chest heart surgery, they are highly immu- nocompromised and susceptible to opportunistic infections.8 Patients may be subjected to ECMO treatment for a prolonged duration of up to several months; thus, their potential expo- sure to waterborne pathogens must be assessed.8 University Hospitals Birmingham (UHB) NHS Foundation


Trust is a tertiary referral teaching hospital in Birmingham, United Kingdom, that provides clinical services to nearly 1 million patients every year. At UHB, ECMO devices are used regularly for patients in critical care with cardiac and/or respiratory failure. Here, we report the results of weekly microbiological water sampling after decontamination following the manufacturer’s (ie, Maquet’s) guidance.


methods Water Sampling


Water samples (100 mL) were collected from the water tank in the 2 Heater Unit 35 (HU35) ECMO devices (Maquet. Rastartt, Germany) used at UHB as described previously by Garvey et al4 (2016). Briefly, water samples were taken weekly before and after the disinfection of each HU35, while the device was running. The neutralizer sodium thiosulphate added to all water samples, which were processed on the day of collection. Every 2 weeks, selected water samples (100 mL) were also sent on the day of testing (at 4°C) to the Myco- bacterium Reference Laboratory (MRL, Public Health England, Heart of EnglandNHSFoundation Trust, Birmingham, UK) for mycobacterium testing. These samples were assessed using standard operating procedures.9 No enumeration of M. chimaera from water sampling was undertaken; the MRL just confirmed presence or absence of M. chimaera.


Isolation and Characterization of Gram-Negative Bacteria


Any suspected Gram-negative isolates growing on the mem- brane filtration agar plates were identified using matrix assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF MS, Vitek MS, bioMèrieux, Marcy-l'Étoile, France) and Vitek (Biomerieux). The water circuit of each HU35 comprises a pump, water


tank, couplings, and tubing for the HU35. Prior to 2017, tubing for each HU35 was replaced every 6 months. Since January 2017, in addition to the tubing being replaced at 6-month intervals, the tubing was replaced after every high-level disinfection.10


Decontamination


At UHB, decontamination of each HU35 was carried out according to the manufacturer’s guidance as follows.10


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