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Hidden Epidemic of Fatal Infections Linked to Heart Surgeries

Heart surgery scar
Heart surgery scar.
Photograph by Niclas Holmqvist, Flickr (CC).

A slow-brewing epidemic of a little-known, potentially fatal bacterial infection appears to be building among cardiac-surgery patients. The physicians who write the blog Controversies in Hospital Infection Prevention—all three of whom work at the University of Iowa—are so concerned about it that they are publicizing one of their own patients (within the bounds of medical privacy) to alert the rest of medicine.

The infection is Mycobacterium chimaera, which does not normally cause disease in humans, but is found in water and soil. The source is troubling and odd: spray from the fan of a heater-cooler device used to control the temperature of blood during a cardiac bypass, which contaminates both the otherwise-sterile operating field, and also any implants—a new valve, a vascular graft—being placed in or around the heart.

The Food and Drug Administration revealed last October that since 2010, it has been told of 32 cases of infection occurring in this manner, eight in the United States and 24 in Europe. The Centers for Disease Control and Prevention followed up with an alert shortly afterward. Papers in two medical journals last year described clusters of cases in cardiac patients in Europe, in hospitals in SwitzerlandGermany and the Netherlands. There has been one publicly acknowledged cluster in the US as well, in a hospital in York, Penn., which triggered an alert from the Pennsylvania Department of Health.

But, Mike Edmond told me: “We believe that, given what we know of how many patients are affected, this is probably just the tip of the iceberg.”

Given what we know of how many patients are affected, this is probably just the tip of the iceberg.

Edmond is an infectious disease physician and the chief quality officer at the University of Iowa Hospitals and Clinics, and a colleague of physicians Eli Perencevich and Dan Diekema; the three of them write the blog together. He told me they were aware of the FDA and CDC alerts and had checked and cleaned their hospitals’ devices; but they became more concerned when a patient from their hospital—who had had cardiac surgery in 2012—returned with an unexplained fever. After prolonged examinations that included a bone-marrow biopsy, the patient was found to be infected with M. chimaera that no doubt came from the device used during surgery.

Because of privacy, Edmond couldn’t reveal this patient’s fate. In the European and Pennsylvania case clusters, up to half of the victims died.

He told me it was likely this patient could have slipped through the cracks, for several reasons—reasons which might well exist in other areas of the US too. Iowa is rural, and the medical center where the three physicians work is both the apex of the pyramid medically and not necessarily accessible geographically. “A lot of patients don’t receive their follow-up post-operative care in our hospital,” he said. “They go back to their local doctor, so we don’t see them.”

After the access issue, there’s the problem of recognition. “There are many unusual and problematic features of trying to work this up,” Edmond said. “One is the long duration of time from surgery to diagnosis. This is a very slow growing organism; it takes quite a while for symptoms to even develop in an infected patient. And the other problem is that we don’t normally order Mycobacterium blood cultures on patients unless they are immunosuppressed. In an AIDS patient who has ongoing fevers that we cannot explain, we’ll order them, and you might you order them in a transplant patient. But not in someone who is immunologically competent.”

The kind of heater-cooler responsible for the infections.
The kind of heater-cooler responsible for the infections.

If this is diagnosed—which means, if physicians think to order a test to look for it— patients face a hard road ahead. “Mycobacterium infections are really tough,” he said. “They require more than one drug, the drugs are toxic, and in the case of people who have implants, a heart valve, a graft—and from the literature, most of these patients do—that implant has to be removed. The actual implant has the organism growing on it.”

Just at Iowa—not the largest cardiac program in the US—this has triggered a re-examination of 1,500 patients.

“Even though we have only found one case, we know there could be other patients like this out there,” Edmond said. “And there may be physicians out there trying to work that up and not coming up with an answer. We felt it is important to try to raise awareness, because who knows how many of these might be out there, lingering without a diagnosis.”

Iowa has sent a letter to every heart surgery patient from the past four years, which refers them to an explanatory webpage and a 24-hour 800-number (866-514-0863) staffed by nurses who walk callers through a list of symptoms: “fever lasting more than one week; pain, redness, heat, or pus around a surgical incision; night sweats; joint pain; muscle pain; loss of energy; and failure to gain weight or grow (in infants).” Depending on the answers, patients are referred for follow-up care.

Since the three physicians put up their post on Tuesday, they have heard from physicians in other locations also struggling with this. (A few have commented on the blog.) But Edmond said the point is not only to alert doctors.

“We also need patients to be aware of this,” he said. “Say your surgery was last December; based on the known cases, there is a 4-year timeline in which you could develop symptoms. And most infectious disease physicians at this point are not aware this is even going on.”

If you are a physician who would like to know more or share your experience, head to the HAI Controversies blog to comment or to email the authors.

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