An outbreak in slow motion

Not too many infections have crude mortality rates of 50% or more. Those that do generally inspire fear, alarm, and media coverage (see: avian influenza, Ebola). Hence my surprise that the heater-cooler device (HCD)-associated M. chimaera global outbreak has attracted so little attention in clinical, public health and media circles.

Now, over a year since Hugo Sax and his group first described the role of HCDs in invasive M. chimaera infections, this may be about to change. Why? Because today the CDC published (in MMWR) the results of whole genome sequencing from 11 patients and 5 HCDs in Iowa and two centers in Pennsylvania (the Iowa isolates were from our patients and devices). The results confirm what we’ve suspected from the beginning: this is a point source outbreak, and the likely source is the factory in Germany where the HCDs are manufactured. There are now several media outlets that have picked up the story (here's one from NY Times and one from Consumer Reports). 

In response to these findings, both CDC and FDA are making new recommendations for centers that use the implicated HCD (the LivaNova (formerly Sorin) 3T). You can read the details for yourself, but the major new recommendations are for provider and patient notification (not just for centers that have detected cases, but for all that use the devices), and from the FDA, a recommendation to remove any HCDs linked to contamination or clinical cases, and to transition away from use of the 3T model entirely (the alert states that use of 3T units manufactured prior to September 2014 “should be limited to emergent and/or life-threatening situations if no other heater cooler devices are available”). 

The problem is that the 3T has at least 60% of the HCD market, and if all hospitals stopped using them (even just those manufactured prior to September 2014), there wouldn’t be enough other units to fill the void. Also important to note: the FDA alert provides evidence that some 3T’s manufactured after September 2014 have been found to be contaminated with M chimaera. Whether the post-2014 contamination represents point-source contamination or not, it’s a huge problem and calls into question the use of the manufacture date in decision-making.

The bottom line is that the 3T is a proven bio-aerosol generator, and should not be in the same room as the operative field. No amount of focus on cleaning and disinfection, the direction of the exhaust fan, or the results of water cultures (which, as we’ve pointed out, are not actionable) changes that.


  1. Dan, Well said, but what the FDA and CDC's recent alerts arguably overlook is that heater-cooler models other than the Sorin 3T model, types of mycobacteria other than M. chimaera, including M. abscesses and MAI, and other point sources, namely, a hospital's contaminated tapwater maybe playing more of a role in these outbreaks and clusters of infections than currently acknowledged. Health alerts that focus almost exclusively on an overseas manufacturing plant as the primary point source and cause of these infections can hinder US hospitals from implementing important corrective actions here at home, namely, using sterile water in the heater cooler devices, periodically monitoring the hospital's tap water to ensure its levels of mycobacteria are safe, and either affectively decontaminating or replacing heater-cooler devices found to be contaminated. It is unclear to me why these most recent federal health alerts do not discuss these other important corrective and preventive actions.

    1. Hi Lawrence, You make a very good point--there is a general issue of having these devices in the OR, and a need to follow the steps you suggest while awaiting redesigned devices that are unable to produce this risk (e.g. that don't use water, that contain HEPA filters, UV, or other approaches to prevent bio-aerosols). But I think the unique aspects of the M chimaera outbreak (including a clinical syndrome of disseminated MAC infection in otherwise immunocompetent hosts that is really quite novel and likely to go unrecognized without widespread notification) justify the CDC and FDA focus on this particular device, and this particular contamination event. I liken it to a situation where one finds a multistate outbreak of central line bloodstream infections (CLABSI) due to Serratia that are linked to contaminated IV solutions. There are certain steps that must be taken to address that particular outbreak, while still recognizing that continued efforts to reduce risk of CLABSI generally are still important. Similarly here, we need to directly address this multinational M chimaera outbreak, at the same time laying the groundwork for a complete rethinking of the design, care and use of HCDs generally. Thanks for your interest in the blog. Dan

  2. is there a list of hospitals in the US that use t his machine?


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