Mycobacterium chimaera update: A “must listen” from ECCMID

We’ve posted several times about the horrible M. chimaera outbreak linked to heater-cooler units (HCUs) used during cardiac bypass surgery. As we’ve addressed the problem here at Iowa, we’ve become increasingly frustrated (and dumbfounded) at the lack of available information about the clinical and epidemiological features of the outbreak itself, and at the general lack of urgency about this ongoing and grave risk to patients. 

Fortunately, Dr. Jakko van Ingen gave an excellent talk at ECCMID that answers several important questions we’ve had about this outbreak, confirming some of the things we’ve heard (“in confidence”, I assume for political or legal reasons) on various conference calls and email strings. I urge you to take 30 minutes of your time to listen to his talk, all the way to the end of the Q&A period. 

Aside from being an extremely entertaining speaker, Jakko addresses several key questions, including: 
  • Is this a clonal outbreak? YES. Slide 29 reports whole genome sequencing data that clusters the isolates from Sorin 3T units and infected patients (within just 2-3 SNPs), and further discussion (during Q&A session) confirms that isolates from other European countries are also in this cluster.
  • Were the HCUs already contaminated prior to being shipped to end users? YES. Listen carefully to the last question and answer.
  • Does this particular outbreak primarily involve one make/model of HCU? YES. While nontuberculous mycobacteria have been isolated from other types of HCUs, the specific M. chimaera cluster in this case involves Sorin 3T units. 
  • Is the invasive, disseminated, high crude mortality form of the illness restricted to those patients with implants (e.g. valves, grafts)? YES. The life-threatening disseminated infection appears to require some prosthetic material to which the organism can adhere, protecting itself (via biofilm formation) from host defense. According to Dr. van Ingen, case finding in the Netherlands is now limited to those with implants, and does not include standard non-valve, non-implant CABG patients.
  • Is it possible to mount an effective, rapid national response to this urgent problem? YES. Slide 18 details the Dutch response, which involved discontinuing all non-urgent cardiac surgery until HCUs were placed outside of ORs (which was done within 48 hours). As we learned here when we did the same thing, it is amazing what you can accomplish when you are left with no other option. 
  • Is opening up a Sorin 3T HCU a frightening experience? YES. I’m sure I’ll have nightmares about these water-stained, biofilm-befouled devices for a long time (see below for one image from Garvey, et al). 

What are the implications? 
  • HCUs are not safe to operate in an OR. The air exhausting from the HCU ventilation fan must be physically separated from the air in the OR, and the easiest way to do that is to remove them from the OR (and maintain the OR at positive pressure, of course). 
  • Everyone using Sorin 3T HCUs should assume that they may have exposed patients to M. chimaera, until more is known about the details of the point-source. Contaminated units cannot be disinfected even with the more intensive protocols currently recommended. In addition, only a few labs are capable of properly performing NTM cultures of water samples, so negative water cultures are of limited value and could be falsely reassuring.
  • A much more active national patient and provider notification is needed. Our experience is similar to that of others: identified cases would never have been found had it not been for aggressive and active case-finding. There are undoubtedly others currently being treated with immunosuppression for sarcoidosis or some other “granulomatous process of uncertain etiology” who actually have undiagnosed disseminated M. chimaera disease.
Below I've pasted an epidemic curve of non-tuberculous mycobacteria (NTM) cases linked to HCUs (inclusive of M. chimaera, but also isolates not identified to species level and other NTM such as rapid-growers), including cases reported to FDA from US (blue bars) and abroad (red). This outbreak isn't over, and the fact that there are still hospitals performing cardiac surgery with their Sorin 3T HCUs inside of the OR is extremely distressing.


  1. Great post, Dan! The presentation by Jakko van Ingen is superb. What continues to amaze me is the lack of response by CDC, and the ineffective response of FDA. It's appalling and it doesn't have to be that way, as the Dutch have shown us.

  2. Great talk and post. I'm at a loss as to why there hasn't been a national response in the US. Are they just distracted and stretched thin? I hope this talk and post jump start the discussions and lead to a response.

  3. Very interesting however the same question remains to be answered to those sites that cannot meet the Distance in the Instructions for use to take the piece of equipment out of the OR:
    For the relocation of this equipment the manufacturer has a 5 meter (16.4 feet) Quote from the Manufacture's instructions for use (IFU): "To minimize noise exposure and avoid disturbing the air flow in the operating room, the system can be operated in an adjoining room provided that the technical construction allows for this setup. In this case, the system can be controlled via the HLM system panel. The length of the tubing betweenthe heater-cooler and heat exchangers and the heating blanket must not exceed 5 m (16.4 ft).". what are users out there doing if in order to relocate outside the OR you will have to extend the tubing connection outside the recommended distance of the 16.4 feet (5m).? Non compliant with IFU's ? See more at:

  4. Thanks for the posting Dan. I have tried to access the audio of the speakers presentation but is seems that only the slides are now available?
    Secondly was there any mention of the manufacturing plant that the contaminated HCUs are coming from or is the contamination occurring at all plants?
    From my reading of the FDA documents it seems that these HCUs are manufactured in more than one plant and in different countries.
    Glenys Harrington, Consultant, Infection Control Consultancy(ICC), Melbourne Australia.

  5. Thanks Carmen and Glenys for your comments.

    Carmen, I agree that the logistics of removal are not straightforward, and may require a trade-off between strict adherence to manufacturers IFU (which are clearly not providing a safe environment for patients) and the need to remove an unsafe device from the OR, while ensuring that any deviation from IFU doesn't compromise the basic function of the HCU (which is to heat and cool things). The onus should be on the device manufacturer to promptly address a clear hazard, and the slow response to this problem by all parties is alarming.

    Glenys, I am not sure why the audio is no longer accessible, I will try to find out from someone on ECCMID planning committee. I don't recall that he mentioned the specific plant from which the water was sampled and organism sequenced. Again, though, the amount of time that has passed without publication of the sequencing data from isolates obtained from patients and devices in US and Europe is very frustrating. This is an outbreak, taking place at a time when an entire genome can be sequenced in hours--the questions of whether the M chimaera cases represent a point source outbreak, the likely point of contamination of devices with M chimaera, etc., should have been answered (seemingly they have) and should by now be widely known.


  6. My Father recently passed away from this horrendous bacteria, in the UK and am at a loss as to why this is not being highlighted?!? I'm trying to gather as much information as I can to take this to the media to help get this out there!


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