A new study implicates a cardiac surgery heater cooler in the spread of a potentially deadly post-surgical infection.

The study was published by the Society for Healthcare Epidemiology of America in the journal Infection Control & Hospital Epidemiology.

Researchers say the invasive and slow-growing bacterium Mycobacterium chimaera can contaminate a cardiac surgery heater cooler, which then transmits the bacterium to patients undergoing surgery.

The devices investigated in this study are used to control heat exchange in heart-lung machines used during open-heart surgery.

Devices like these are used in around 250,000 surgeries every year in the U.S., according to the Centers for Disease Control.

Researchers in the study say they found M. chimaera bacteria in the water circuits of the LivaNova 3T cardiac surgery heater cooler.

LivaNova previously operated under the name Sorin Group Deutschland. The 3T unit mentioned in the study is used in most hospitals throughout the world.

Researchers also reported finding M. chimaera bacteria in air samples taken from operating rooms in which the LivaNova 3T was in use.

With a previous reputation for causing lung infections, M. chimaera can cause significant problems for heart surgery patients. Treatment of an invasive post-surgical M. chimaera infection requires more surgery and prolonged antibiotic therapy.

The study explains what has been described as a global outbreak of M. chimera infections found in patients who had surgery using these devices. The study’s lead author Dr. Rami Sommerstein expressed surprise that this global outbreak could go years without being noticed.

Dr. Sommerstein said now that the source of these infections is known, health care providers must take action to ensure that these infections stop. He says the most important thing hospitals can do is to remove cardiac surgery heater cooler units from the operating room and other critical areas.

The researchers made particular recommendations to help minimize the risk of future M. chimera infections. Hospital staff must strictly separate cardiac heater coolers from the air in critical medical areas. Clinicians need to be educated on the risks associated with these devices.

The researchers also called for screening of patients who had undergone open heart surgery, heart transplantation, or were otherwise exposed to potential infection by the use of a cardiac heater cooler.

FDA Issues Cardiac Surgery Heater Cooler Warning

The FDA has also been tracking this issue. Investigations found M. chimaera bacteria at the German facility where the LivaNova 3T machines were manufactured, suggesting that they could have been contaminated during the manufacturing process.

In October 2015, the agency reported it had received 32 reports of patients who had developed post-surgical infections that could be related to the use of these cardiac heater coolers. A follow-up report in June 2016 specifically named the LivaNova 3T as being linked to a risk of infection.

Within the U.S., 28 infections have been confirmed in three different states, according to the Centers for Disease Control.

These infections can take months or in some cases years to develop. Symptoms that may indicate an infection include prolonged fever, night sweats, muscle aches, weight loss, and fatigue, according to the CDC.