LIVN LivaNova PLC

Researchers linked a rare but potentially lethal bacterial infection that has affected patients in at least three states to contamination of a device used in open-heart surgery centers. At least four patients in the U.S. have died.

In a report published Thursday by the U.S. Centers for Disease Control and Prevention, the researchers said a genomic analysis "strongly" suggests that the infections arose from a common source: a heater-cooler device that helps control a patient's body temperature during open-heart operations.

The device, called the Stö ckert 3T, is manufactured by LivaNova PLC of the U.K. and accounts for an estimated 60% share of the U.S. market for the machines, according to an account of the research published in the CDC's Morbidity and Mortality Weekly report.

The report is the latest development in an 18-month effort to solve a mystery over the origin of the unusual infection, which first surfaced in a cluster of patients in Switzerland in the spring of 2015. Some patients in Germany have also been infected.

Since the Swiss outbreak, the CDC has learned of 28 cases in the U.S., including 21 in Pennsylvania, five in Iowa and two in Michigan, a spokeswoman said. The four associated deaths were in Pennsylvania.

Late last year, the U.S. Food and Drug Administration blocked imports into the U.S. of the LivaNova device, manufactured in Germany, after issuing a warning letter related to manufacturing violations at the company. The FDA didn't ask hospitals to stop using existing units, though the agency and the CDC have issued recommendations for reducing risk of the infections.

LivaNova was recently formed by the merger of Sorin S.p.A. and Cyberonics Inc. The company said it aware of the new report and is "working with regulators to develop a solution that addresses their concerns and assures continued clinician access to this important device, which enables lifesaving cardiac surgery."

The devices circulate water to warm or cool patients undergoing coronary artery bypass surgery or such other procedures to replace heart valves or diseased aortic tissue. The water doesn't come in contact with patients, but the FDA has said it is possible for a bacterium that gets established in the device to become aerosolized in the operating room through the device's exhaust vent.

The culprit is an organism called Mycobacterium chimaera, one species of what are called nontuberculous mycobacteria that are common in nature and found in water, soil and tap water. Generally they aren't harmful to people, but the FDA says they can cause serious infections in patients who are severely ill or who have weakened immune systems.

For the new report, researchers sequenced samples of M. chimaera taken from 11 patients infected in Iowa and Pennsylvania and from five of the devices used in hospitals in those states.

All had the "identical fingerprint," said Dr. Michael Bell, deputy director of the CDC's division of health-care quality promotion. "We definitely have a multistate outbreak related to this one machine." The results almost certainly mean "the machines were shipped with the contamination," he said.

How many patients may have been infected by the contaminated device is difficult to determine. The infection is especially slow-growing, said Charles Daley, chief of the division of mycobacterial and respiratory infections at National Jewish Health, Denver, and often doesn't cause symptoms for months or even years. Neither patients nor doctors even connect symptoms to the operation.

He said open-heart-surgery patients who experience such symptoms as chills, fatigue, fever, and unintended weight loss even long after their operation should be tested for the infection. Most of the confirmed patients had a valve or other prosthetic tissue implanted during their surgery, said Dr. Daley, who is a co-author of the report.

"Once valves get seeded with these organisms, it becomes very difficult to treat," he said.

The evidence so far suggests that somewhere between one in 100 and one in 1,000 patients whose surgeries involved the device might develop an infection. Caught early, it is generally easy to treat, he said. "It may be low-risk, but once it happens, it's very bad for the patient."

Previous reports have shown that cases in Europe are linked to samples of M. chimaera found at the company's manufacturing facility in Germany. Efforts are under way to determine whether infections in the U.S. patients arose from the same source.

Write to Ron Winslow at ron.winslow@wsj.com

(END) Dow Jones Newswires

October 13, 2016 13:35 ET (17:35 GMT)

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