Scientists from Australia and New Zealand say that bacteria contamination of a surgical machine may be transferred to patients during heart surgery.

The finding supports what many have already suspected about a string of post-surgical mycobacteria infections that have afflicted patients months and sometimes years after completion of open heart surgery. Infections like these have been associated with contamination found in the Stöckert 3T heater-cooler system manufactured by Liva Nova.

In the study, researchers from the Peter Doherty Institute for Infection and Immunity collected dozens of samples of bacteria from surgical heater-cooler units, plus a few other samples from affected patients.

Analysis of the samples’ genomes revealed the bacteria were genetically similar to bacteria taken from machines in the Northern Hemisphere.

This match suggests the pathogens from both sets of samples originated from a point source, the scientists say. They were able to confirm that the three known cases of infection reported in Australia are linked to this bacteria contamination of a surgical machine.

The researchers say these findings show the potential for bacterial contamination of a surgical machine to become a worldwide problem, based on the dissemination of these devices all over the world. They believe the heater-cooler units may have been contaminated while they were being manufactured.

The researchers say they are now working on a fast diagnostic test that will use whole-genome sequencing technology to give patients a reliable diagnosis.

The Effects of Bacteria Contamination of a Surgical Machine

The Stöckert 3T heater-cooler system is used in conjunction with other surgical equipment to keep the patient’s body temperature under control during heart surgery. It works by transferring temperature-controlled water to and from other devices that control the patient’s blood and organ temperature.

Because temperature control can substantially improve patient outcomes, heater-cooler devices like these are in widespread use. In the U.S., about 250,000 open heart bypass procedures are performed every year, and 60 percent of those surgeries use the type of device that has been associated with these infections.

While the water in the Stöckert 3T does not come into contact with the patient, contamination can take hold elsewhere inside the machine. Researchers believe bacteria can be forced through the machine’s exhaust system and into the air of the operating room, where it can then find its way to the open incision on the patient’s body.

The mycobacteria associated with these infections are actually very common, and they rarely make a healthy person sick. But trouble can happen once these mycobacteria get inside the body of a surgical patient.

The resulting infection may remain latent for a long time. Symptoms may not appear until months or even over a year after surgery. Typical symptoms may include night sweats, muscle aches, fatigue, weight loss, or fever that can’t be explained otherwise.

Both the Centers for Disease Control and the U.S. Food and Drug Administration have issued several communications addressing the risk of bacteria contamination of a surgical device. The CDC notes that the risk of infection is very low, but patients who do develop an infection can be at risk for serious complications and possibly death.