A solution for global hygienic challenges regarding the application of heater-cooler systems in cardiac surgery

71.759 surgical procedures were performed in 2019 with the aid of cardiopulmonary bypass in Germany. To adjust the patient's body temperature on extracorporeal circulation, the application of a heater-cooler unit (HCU) is mandatory. However, in case of insufficient sanitisation of HCU, life-threatening infections can be transmitted by the device to the patients, including Legionella bacteria, Mycobacterium chimaera, Pseudomonas aeruginosa. To avoid disease transmission, as a requirement for safe medical practice established by regulatory authorities, HCUs must be regularly disinfected by hazardous chemicals posing a danger for both handling humans and the environment. Therefore, to comply with regulations, HCU manufacturers have introduced both timely and financially extensive sanitisation procedures. Our paper describes a novel, effective and easy to handle disinfection method for the above problematics without utilising hazardous chemicals. The method's technical principle is electrolysis, resulting in drinking water quality regarding the analysed germs in the worldwide most commonly utilised heater-cooler device. The main aim of the study was to prove the efficacy and reliability of the device cleansing process. Furthermore, the economic impact of the novel method was evaluated. Therefore, we have undertaken 60 microbiological sampling series between December 2019 and November 2020 from a conventional HCU (3T LivaNova, Germany). During the total investigational period, no contamination with Pseudomonas aeruginosa or Legionellae could have been demonstrated in the HCU. The extreme slow-growing nontuberculous M. chimaera was detected only in one sample obtained from diamond electrode cleansed HCU water, and source of contamination was promptly eliminated by a simple technical modification of the device test-site. Additionally, the diamond electrode application is beneficial for eliminating potentially hazardous cleansing material from the process, which may affect otherwise both patients operated on cardiopulmonary bypass and the perfusionists.

Real-time PCR, the best approaches for rapid testing for Mycobacterium chimaera detection in heater cooler units and extracorporeal membrane oxygenation

According to recent investigations, the risk of M. chimaera contamination of heater-cooler units (HCUs) has reached global proportions. Our aim was to field evaluate a protocol for early detection of M. chimaera contamination. We assessed the presence of viable M. chimaera in 395 water samples obtained from 48 devices (HCUs and extracorporeal membrane oxygenation) by Real Time PCR. Thirty devices were NTM positive, of which 14 were contaminated with M. chimaera. The most frequently contaminated devices were the Stockert 3T. Noteworthy, Stockert 3T devices were positive for M. chimaera. In conclusion, this study introduces novel PMA-PCR designed to specifically detect M. chimaera in HCUs and ECMO devices; this method can replace the culture method for continuous microbiological surveillance. The timely detection of M. chimaera contamination can then be used to improve effective management of the devices.

Mycobacterium chimaera chorioretinitis as a biomarker of systemic disease activity following nosocomial acquisition during cardiopulmonary bypass

Objectives: To understand the role of ophthalmoscopic examination (dilated retina examination and widefield fundus photography) in the diagnosis and management of nosocomial acquisition of Mycobacterium chimaera following open heart surgery with cardiopulmonary bypass utilizing a heater-cooler unit, an entity that is associated with >50% mortality during the worldwide outbreak that has occurred since 2013.Methods: Case report with review of previous cases.Results: Signature Mycobacterium chimaera chorioretinal lesions can be used as a diagnostic sign and a biomarker for assessment of treatment efficacy.Conclusions: Ophthalmologic examination can play a key role in diagnosis and management of systemic Mycobacterium chimaera following cardiopulmonary bypass; such examinations may yield earlier diagnosis, diminishing mortality rates.

Cluster of invasive Mycobacteria chimaera infections following cardiac surgery demonstrating novel clinical features and risks of aortic valve replacement

There is a global outbreak of infections due to Mycobacterium chimaera associated with cardiac surgery. The most serious infections involve prosthetic material implantation, and all have followed surgical procedures involving cardiopulmonary bypass. We describe a cluster of four cases following cardiac surgery at a tertiary referral centre in Sydney, Australia. We report novel clinical findings, including haemolysis and kidney rupture possibly related to immune reconstitution inflammatory syndrome. The positive effect of corticosteroids on haemodynamic function in two cases and the failure of currently recommended antimicrobial therapy to sterilise prosthetic valve material in the absence of surgery despite months of treatment are also critically examined. Positron emission tomography was positive in two cases despite normal transoesophageal echocardiograms. The proportion of cases with M. chimaera infection after aortic valve replacement (4/890, 0.45%; 95% confidence interval 0.18-1.15%) was significantly higher than after all other cardiothoracic surgical procedures (0/2433, 0%; 95% confidence interval 0-0.16%).

Mycobacterium chimaera in heater-cooler units: new technical approach for treatment, cleaning and disinfection protocol

Mycobacterium chimaera infections have mainly been associated with the heater-cooler unit (HCU) and, ultimately, linked to contaminated aerosols in the operation room. The contamination status of HCUs seems to be influenced by the maintenance, therefore, according to the manufacturer's recommendations, peracetic acid (Puristeril) was introduced to increase HCU cleaning and disinfection protocol maintenance. Aerosol dispersion from Puristeril during maintenance can cause adverse effects to nearby workers. We aim to describe our technique to reduce the impact of Puristeril on operating room staff and to limit dispersion of its aerosol in the environment by performing the cleaning procedure through a closed circuit.

Microbiological monitoring of heater-cooler unit to keep free of Mycobacterium chimaera infection

INTRODUCTION

The association of Mycobacterium chimaera infection in patients undergoing cardiopulmonary bypass (CPB) with the use of heater-cooler units (HCU) has been reported in various literature. We described microbiological monitoring and the extent of microbiological contamination of HCUs utilized in our centre and strategies employed to reduce the high microbial load.

METHODS

Since August 2016, we have been following the new Instructions for Use from the manufacturer for the cleaning and disinfection of three units of Stöckert 3T and four units of Stöckert 1T HCU at the National Heart Centre Singapore. Microbiological monitoring began in January 2017 and included acid-fast bacilli (AFB) culture, Pseudomonas aeruginosa, total colony and total coliform count. Methods, such as increasing disinfection frequency and making the HCU inactive by keeping it empty in storage, were used to reduce the high colony count.

RESULTS

All three units of Stöckert 3T and two units of Stöckert 1T were contaminated with Mycobacterium chimaera. Pseudomonas aeruginosa and total coliform count were consistently <1 colony-forming unit (CFU)/100 mL in every water sample of each HCU. High colony counts were encountered initially in all units. Step-up frequency of disinfection was found to be not as effective as keeping the HCU inactive in bringing the total colony count to an acceptable level.

CONCLUSIONS

All monitoring and maintenance measures of HCUs need to be established and maintained to mitigate potential infection risks to patients. Strict adherence to all cleaning and disinfection processes and keeping the HCU inactive maintained the water quality of the HCU at acceptable levels.

Clinical implications of Mycobacterium chimaera detection in thermoregulatory devices used for extracorporeal membrane oxygenation (ECMO), Germany, 2015 to 2016

Mycobacterium chimaera, a non-tuberculous mycobacterium, was recently identified as causative agent of deep-seated infections in patients who had previously undergone open-chest cardiac surgery. Outbreak investigations suggested an aerosol-borne pathogen transmission originating from water contained in heater-cooler units (HCUs) used during cardiac surgery. Similar thermoregulatory devices are used for extracorporeal membrane oxygenation (ECMO) and M. chimaera might also be detectable in ECMO treatment settings. We performed a prospective microbiological study investigating the occurrence of M. chimaera in water from ECMO systems and in environmental samples, and a retrospective clinical review of possible ECMO-related mycobacterial infections among patients in a pneumological intensive care unit. We detected M. chimaera in 9 of 18 water samples from 10 different thermoregulatory ECMO devices; no mycobacteria were found in the nine room air samples and other environmental samples. Among 118 ECMO patients, 76 had bronchial specimens analysed for mycobacteria and M. chimaera was found in three individuals without signs of mycobacterial infection at the time of sampling. We conclude that M. chimaera can be detected in water samples from ECMO-associated thermoregulatory devices and might potentially pose patients at risk of infection. Further research is warranted to elucidate the clinical significance of M. chimaera in ECMO treatment settings.