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Study: 37% of heater-cooler devices contaminated with M. chimaera
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More than one-third of heater-cooler devices sampled during a recent study were contaminated with Mycobacterium chimaera, researchers said, highlighting the risk of the machines to cause nosocomial infections.
M. chimaera is a slow-growing species of nontuberculosis mycobacteria (NTM) commonly found in soil and water, according to the CDC. It rarely makes people sick but can cause fatal postsurgical infections that are often difficult to diagnose, researchers have said.
Heater-cooler devices (HCDs) are used with heart-lung machines to regulate body temperature during cardiothoracic surgeries and other medical procedures. A widely used brand of HCD, the LivaNova 3T, has been linked to a global outbreak of M. chimaera infections, leading to warnings from the CDC and FDA about their safety.
John Rihs, vice president of laboratory services at Special Pathogens Laboratory in Pittsburgh, presented findings at the 44th Annual Conference of the Association of Professionals in Infection Control and Epidemiology (APIC) that underscore the extent of the possible contamination.
Rihs and colleagues collected 653 water samples from 89 HCDs located across the U.S. between July 2015 and December 2016 and isolated M. chimaera from 37% of them. Overall, NTM were isolated from 51% of the devices; in addition to M. chimaera, Rihs and colleagues also found M. abscessus/chelonae, M. chlorophenolicum, M. cookii, M. gordonae, M. nebraskense, M. palustre and M. timonense.
Rihs said the results of the study were “consistent with previous findings” and characterized the extent of contamination with M. chimaera, a rare organism, in HCDs from across the country as being “surprising.”
“Some devices remained positive for M. chimaera for months, indicating that disinfection can be difficult and routine testing is advisable,” Rihs said in a news release. “Beyond M. chimaera, we found other NTM species, Legionella, and fungi, indicating these units are capable of supporting a diverse microbial population.”
Symptoms of M. chimaera infection, including fatigue, fever, sweats, dyspnea, weight loss and cough, are often delayed and can be difficult to distinguish from other infections, making it hard to find cases, researchers have said. One study showed that patients were commonly misdiagnosed, often with sarcoidosis. Patients can become infected by water contaminated with M. chimaera that has been aerosolized by HCDs during surgery.
Prior research has shown that contaminated LivaNova 3Ts were most likely exposed to M. chimaera at the German plant where they are manufactured. Researchers have cautioned that the devices, which make up most of the global market for HCDs, should be considered contaminated regardless of when they were made or whether they have tested negative for M. chimaera.
Researchers have advised hospitals on how to separate their HCDs, which are difficult to decontaminate, from the operative field to keep aerosolized M. chimaera away from patients and how to locate and notify patients who may have been exposed during cardiac surgery. They said any symptomatic patient who has been exposed to a LivaNova 3T since 2006, the year hospitals began using the device, should have M. chimaera in their differential diagnosis.
Rihs and colleagues said 11 HCDs that originally tested negative for NTM in their study had positive cultures in subsequent samples. They said 15% of the 653 samples they cultured were uninterpretable because of high levels of bacterial and fungal contamination.
“These results highlight the importance of monitoring the decontamination and maintenance schedules of these devices to minimize the risk of patient harm,” Linda Greene, RN, MPS, CIC, FAPIC, 2017 APIC president, said in the news release. “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.” – by Gerard Gallagher
Reference:
Rihs J, et al. Abstract 1207. Presented at: Association for Professionals in Infection Control and Epidemiology Annual Conference; June 14-16, 2017; Portland, Oregon.
Disclosure: Rihs reports no relevant financial disclosures.
Perspective
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Heather A. Hohenberger, MSN, RN, CIC, CNOR, CPHQ, FAPIC
There are several clinical implications, both for intraoperative and infection prevention personnel, found in the heater-cooler research performed by Rihs and colleagues. For the intraoperative team, it appears that our previous processes established to decrease cross-contamination risk to the patient may not be sufficient when HCDs are used in surgery. Establishing a routine schedule for HCD cleaning and disinfection following device manufacturer’s instructions for use and validating team members’ competency for performing this task have been our primary implementations for decreasing risk to the patient when a HCD is used in surgery. Seeing the results of this study, infection preventionists and the perioperative multidisciplinary team should collaborate to identify additional steps needed to mitigate intraoperative contamination risk when HCD units are used for patient care.
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