Stockert InfectionsIn 2015 and again in 2016, the U.S. Food and Drug Administration (FDA) has warned about dangerous bacterial contamination in heater-cooler devices used in operating rooms nationwide, in particular during cardiac surgeries.
The bacteria, M. chimaera, is a species of nontuberculous mycobacterium (NTM). Nontuberculous mycobacteria (NTM) are organisms naturally found in soil and water. Most people do not become ill but for susceptible individuals, a slowly progressive and destructive disease can occur, the American Lung Association explains.
The NTM bacteria are present in the Stöckert 3T heater-cooler system, the equipment widely used to regulate the patient’s body temperature during surgery. The NTM outbreak was reported by Infection Control & Hospital Epidemiology, the journal of the Society for Healthcare Epidemiology of America. Dr. Rami Sommerstein, of Inselspital, Bern University Hospital in Switzerland, lead author of the study, said, “It is surprising that a global outbreak like this could go unnoticed for years. This dangerous infection has put many patients at risk all over the world.”
The Stöckert 3T heater-cooler is a device used during heart surgeries to keep the patient’s organs and blood at the proper temperature during the procedure. Keeping an ideal body temperature during surgery is known to improve outcome. Heater-cooler devices use water tanks to provide temperature-controlled water to heat exchangers or blankets, which then cool or warm the patient’s body. Water in the circuits does not directly come into contact with the patient, but mycobacteria grow in water, and it is possible for the bacteria to grow in the water used in the heater-cooler system. Contaminated water can aerosolize and transmit bacteria through the device’s exhaust vent into the operating room and to the patient.
Symptoms of NTM infection include persistent or unexplained fever; night sweats; redness, heat, or pus around a surgical incision; muscle aches; unexplained weight loss; or fatigue. The symptoms can take months to appear, even as long as five years, which complicates the task of diagnosing the infections.
The Stӧckert 3T warming-cooling device has been implicated in nontuberculous mycobacteria infections. M. chimaera has been directly linked to contamination in the manufacturing of the Stӧckert 3T Heater-Cooler System (3T) by Sorin Group Deutschland GmbH. The contamination was discovered in September 2014 at the manufacturing facility.
Cleaning the Stöckert 3T heater-cooler does not always eradicate M chimaera. Even after an intensified cleaning and disinfection protocol and the manufacturing facility in Germany, mycobacteria re-emerged.
Alerting Hospitals and Patients to NTM Infection Risk
NTM infections linked to heater-cooler devices have been detected worldwide and hospitals and health authorities, including the CDC and Health Canada, are alerting patients who have had cardiac surgeries where a heater cooler devise was likely used.
A statement from the Society for Healthcare Epidemiology of America (SHEA) in collaboration with Medscape, “strongly suggests” a point-source contamination of LivaNova 3T heater-cooler devices with M. chimaera. But while identify the source of NTM is an important development, finding a solution is the real challenge. The Stöckert 3T is not easy to replace, and there are many in use. Removing heater-cooler devices from operating room could put lives at risk, surgeons say. One solution—building a stainless steel housing for the Stöckert 3T, will take a long time and to achieve air-tightness construction is complex.
Although thousands of patients in the United States have been notified about potential exposure to M. chimaera through the Stöckert 3T and similar devices, the CDC believes many more people may be at risk and are not aware of their exposure. The CDC estimates that more than 250,000 procedures using cardiopulmonary bypass are performed in the United States each year. The CDC estimates that the Stöckert 3T is used in about 60 percent of the US market (LivaNova estimates 70 percent).
The CDC estimates that in hospitals where at least one infection has been identified, the risk of a patient getting an infection from the bacteria was between about one in 100 and one in 1,000. The CDC says that available information suggests that patients who had valves or prosthetic products implanted are at higher risk of NTM infection.
To avoid introducing mycobacteria into the heater-cooler system, the FDA says tap water should never be used to fill, rinse, or top off the 3T’s water tanks. In addition, the heater-cooler’s exhaust vent should be directed away from the surgical field to reduce the risk of exposing the patient to bacteria from the exhaust.
In July 2015, the FDA announced a Class II recall of the Sorin/ Stöckert 3T system. The FDA announcement noted the “potential colonization of organisms, including Mycobacteria, in Sorin Heater Cooler Devices, if proper disinfection and maintenance is not performed per instructions for use.” A Class II recall is the intermediate recall category. Use of the product “may cause temporary or medically reversible adverse health consequences,” but the probability of serious health consequences is remote.
The FDA updated the 3T safety warning in October 2016. The agency said it is “continuing to gather information, issue communications, and assess the situation from both public health and regulatory perspectives” and recommends that facilities “immediately remove from service any heater-cooler devices, accessories, tubing, and connectors that have tested positive for M. chimaera or have been associated with known M. chimaera patient infections at your facility.”
But the FDA acknowledges the benefits of the heater-cooler devices. In the October 2016 update the FDA wrote, “heater-cooler devices are important in patient care and, in appropriately selected patients, the benefits of temperature control necessary during open chest cardiothoracic procedures generally outweigh the risk of infection transmission associated with using these devices.”