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.