Factory contamination of medical devices likely caused potentially fatal infections in 33 open-heart surgery patients in several countries, investigators say.
The patients were sickened with Mycobacterium chimaera bacteria, which can cause infection of the inner lining of the heart and spread to the rest of the body.
Genetic examination of M. chimaera samples suggests that heater-cooler units produced by LivaNova in a factory in Germany were the likely source of infection, according to the study.
The devices help keep a patient's circulating blood and organs at a set temperature during heart bypass procedures, according to the U.S. Centers for Disease Control and Prevention.
Patients became ill in the United States, Australia, Switzerland, Germany, the Netherlands, and the United Kingdom, according to the study. The results appear online July 12 in The Lancet Infectious Diseases.
"Whole genome sequencing is the most powerful tool for tracing pathogen [germ] transmission," study co-author Stefan Niemann said in a journal news release.
"Our study closes the missing gap and provides evidence that the international health-care related M. chimaera outbreak can most likely be attributed to a point source," added Niemann, a professor at the Research Center Borstel in Germany.
However, the researchers said the investigation should not be closed because hospital water systems and another brand of heater-cooler units, Maquet, were also found to be contaminated.
That means the risk of infection might continue despite eliminating contamination at the LivaNova production line.
Infection with M. Chimaera bacteria during open-heart surgery remains rare. But since 2013, more than 100 cases have been reported in the United States, European Union and Australia, and many countries have issued guidelines to reduce the risk of infection.