Experts say alarming results support findings from earlier studies and underscore the importance of rigorous monitoring of device maintenance schedules to minimize the risk of patient harm.
More than one-in-three heater-cooler units inspected over 18-months tested positive for a bacterium linked to fatal infections in open-heart surgery patients, a new study found.
“Our results showed M. chimera (Mycobacterium chimaera) in 37% of units tested and is consistent with previous findings. The extent of contamination from such a rare organism in multiple units from all over the country was surprising,” said John Rihs, vice president of Laboratory Services at Special Pathogens Laboratory, which conducted the research.
“Some devices remained positive for M. chimera for months, indicating that disinfection can be difficult and routine testing is advisable. Beyond M. chimera, we found other NTM (Nontuberculous mycobacteria) species, Legionella, and fungi, indicating these units are capable of supporting a diverse microbial population,” Rihs said in remarks accompanying the study.
The research, presented at the 44th Annual Conference of the Association for Professionals in Infection Control and Epidemiology, examined 563 water samples from 89 heater-cooler units in use at 23 hospitals in 14 states, the District of Columbia and Canada between July 2015 and December 2016.
Thirty-three units tested positive for M. chimaera, and four units were colonized with Legionella. Rihs said researchers were surprised at how contaminated the units were, with 97 cultures deemed uninterpretable due to high levels of bacterial and fungal contamination. Multiple other strains of mycobacteria were also detected in many of the units.
HCUs control the temperature of a patient's blood and organs during heart bypass surgery. The U.S. Food and Drug Administration and the Centers for Disease Control and Prevention already have issued safety warnings that the widely used LivaNova PLC Stӧckert 3T Heater-Cooler System might be contaminated during manufacturing, putting patients at risk for life-threatening infections. Approximately 60% of heart bypass procedures performed in the United States use the Stӧckert device.
HCUs have water tanks that provide temperature-controlled water during surgery through closed circuits. The water does not come into direct contact with the patient. However, the water can aerosolize and transmit bacteria through the air into the environment and to the patient.
APIC President Linda Greene, RN, said the findings “highlight the importance of monitoring the decontamination and maintenance schedules of these devices to minimize the risk of patient harm.”
“Hospitals must follow the cleaning and disinfection instructions provided in the manufacturer's device labeling, as well as updated communications from the FDA and CDC,” she said.
M. chimaera is often found in soil and water but is rarely associated with infections. However, patients exposed to the bacteria through open-heart surgery can develop symptoms that can often take months to emerge. As a result, diagnosis of these infections can be missed or delayed, sometimes for years, making these infections more difficult to treat.
Hospitals were instructed by the CDC and FDA to notify patients who have had open-heart surgery within the last five years that they were potentially at risk for infection. Patients were notified to seek medical advice if they were showing any symptoms or signs of infection, which can be vague or inconspicuous.
On Friday morning, LivaNova spokeswoman Deanna Wilke responded by email to a request for comment. Wilke wrote that the London-based medical device company has developed a three-part remediation plan to address the issue.
“The remediation plan developed by the company consists primarily of a modification of the 3T Heater-Cooler design to include internal sealing and a vacuum system to existing devices,” Wilke said.
"Another part of this plan we are implementing is a no-charge deep disinfection service for 3T Heater-Cooler users who have reported confirmed M. chimaera mycobacterium contamination,” Wilke said. “The deep disinfection service has been approved by numerous local regulatory authorities and is available in many countries around the world. We anticipate expanding the deep disinfection service globally as regulatory approvals are received.
"Finally, the company will continue its program to loan existing 3T Heater-Cooler users a new 3T Heater-Cooler device at no charge, pending regulatory approval and implementation of the vacuum system and deep disinfection service worldwide,” she said.
John Commins is a senior editor at HealthLeaders.