Notes from the Field: Mycobacteria chimaera Infections Associated with Heater-Cooler Unit Use During Cardiopulmonary Bypass Surgery - Los Angeles County, 2012-2016

Mycobacterium chimaera Infections in a Unit of Cardio Surgery: Study at a General Hospital in Padua, Italy

Mycobacterium chimaera is a slow-growing non-tuberculous mycobacterium already known for being able to colonize cardio surgery heater-cooler units (HCUs). This study aims to describe the real magnitude of the phenomenon, providing a methodological protocol and the results of a longitudinal survey. In the period 1 January 2017-23 May 2022, over 1191 samples were collected on 35 HCUs of two different manufacturers. Among them, we identified 118 (10.3%) positive results for M. chimaera. We propose our 4-year biosurveillance experience as a practical model to minimize microbiological patients' risk, suggesting the need for new procedures and interventions for a safer and more ecological cardio surgery.

Infective Endocarditis after Transcatheter Aortic Valve Replacement: Challenges in the Diagnosis and Management

Although initially conceived for high-risk patients who are ineligible for surgical aortic valve replacement (SAVR), transcatheter aortic valve replacement (TAVR) is now recommended in a wider spectrum of indications, including among young patients. However, similar to SAVR, TAVR is also associated with a risk of infectious complications, namely, prosthetic valve endocarditis (PVE). As the number of performed TAVR procedures increases, and despite the low incidence of PVE post-TAVR, clinicians should be familiar with its associated risk factors and clinical presentation. Whereas the diagnosis of native valve endocarditis can be achieved straightforwardly by applying the modified Duke criteria, the diagnosis of PVE is more challenging given its atypical symptoms, the lower sensitivity of the criteria involved, and the low diagnostic yield of conventional echocardiography. Delay in proper management can be associated with increased morbidity and mortality. Therefore, clinicians should have a high index of suspicion and initiate proper work-up according to the severity of the illness, the underlying host, and the local epidemiology of the causative organisms. The most common causative pathogens are Gram-positive bacteria such as Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus spp., and Streptococcus spp. (particularly the viridans group), while less-likely causative pathogens include Gram-negative and fungal pathogens. The high prevalence of antimicrobial resistance complicates the choice of therapy. There remain controversies regarding the optimal management strategies including indications for surgical interventions. Surgical assessment is recommended early in the course of illness and surgical intervention should be considered in selected patients. As in other PVE, the duration of therapy depends on the isolated pathogen, the host, and the clinical response. Since TAVR is a relatively new procedure, the outcome of TAVR-PVE is yet to be fully understood.

Mycobacterium chimaera infections among cardiothoracic surgery patients associated with heater-cooler devices-Kansas and California, 2019

BACKGROUND

In 2015, an international outbreak of Mycobacterium chimaera infections among patients undergoing cardiothoracic surgeries was associated with exposure to contaminated LivaNova 3T heater-cooler devices (HCDs). From June 2017 to October 2020, the Centers for Disease Control and Prevention was notified of 18 patients with M. chimaera infections who had undergone cardiothoracic surgeries at 2 hospitals in Kansas (14 patients) and California (4 patients); 17 had exposure to 3T HCDs. Whole-genome sequencing of the clinical and environmental isolates matched the global outbreak strain identified in 2015.

METHODS

Investigations were conducted at each hospital to determine the cause of ongoing infections. Investigative methods included query of microbiologic records to identify additional cases, medical chart review, observations of operating room setup, HCD use and maintenance practices, and collection of HCD and environmental samples.

RESULTS

Onsite observations identified deviations in the positioning and maintenance of the 3T HCDs from the US Food and Drug Administration (FDA) recommendations and the manufacturer's updated cleaning and disinfection protocols. Additionally, most 3T HCDs had not undergone the recommended vacuum and sealing upgrades by the manufacturer to decrease the dispersal of M. chimaera-containing aerosols into the operating room, despite hospital requests to the manufacturer.

CONCLUSIONS

These findings highlight the need for continued awareness of the risk of M. chimaera infections associated with 3T HCDs, even if the devices are newly manufactured. Hospitals should maintain vigilance in adhering to FDA recommendations and the manufacturer's protocols and in identifying patients with potential M. chimaera infections with exposure to these devices.

Mycobacterium chimaera Outbreak Management and Outcomes at a Large Pediatric Cardiac Surgery Center

BACKGROUND

In 2012, a global outbreak of invasive Mycobacterium chimaera (M. chimaera) infection was identified in patients post-cardiopulmonary bypass (CPB) surgery. Investigations revealed the source to be heater-cooler unit (HCU) exhaust, with point-source contamination discovered at the LivaNova HCU manufacturing plant. We report our experience with affected HCUs at a high-volume pediatric cardiac surgery center in the United States.

METHODS

A multi-disciplinary task force was established for outbreak management, including removing contaminated HCUs from service. Patients identified as exposed to affected HCUs were systematically contacted. A call center was created for patient/family inquiries, and symptomatic patients were assessed using an institutional triage protocol, including lab/culture data and infectious diseases consultation.

RESULTS

CPB surgeries were performed in 4,276 patients (median age 2.1 years, range 0-48.4) between October 2010 and October 2016. Call center volume was highest in the first 6 weeks following patient notification, totaling 307 calls and yielding 70 clinical patient assessments. Presenting symptoms included fatigue (60%), fever (49%), night sweats (46%), myalgias (34%), and weight loss (24%). Among the 70 assessed patients, echocardiogram (n=30), cardiac CT (n=2), cardiac MRI (n=1), and pulmonary CT (n=1) did not reveal abnormalities suggestive of active infection. Infectious diseases consultation occurred in 23 (33%) patients. Acid fast bacilli blood cultures were obtained in 30 patients; all were negative.

CONCLUSIONS

Through a highly coordinated outreach effort, no patients have been found to have M. chimaera infection in the six years after exposure to contaminated HCUs. Ongoing vigilance for cases that may yet manifest is needed.

Prosthetic Valve Endocarditis Diagnosis and Management- New Paradigm Shift Narratives

Prosthetic valve endocarditis (PVE) is a major infectious disease problem due to the increasing numbers of patients undergoing valve replacement surgery. PVE can present diagnostic difficulties echocardiographically, especially when complicating transvascular placement techniques. Moreover, outbreaks of unusual PVE pathogens, such as Mycobacterium chimaera, have presented major diagnostic and therapeutic dilemmas.

Patient notification about suspected hospital-associated outbreaks of invasive mold infections: Considerations for public health and hospital personnel

A common type of fungal disease investigation involves hospital-associated clusters of invasive mold infections (IMIs), which typically occur among immunocompromised patients. Responding to IMI clusters can be challenging for public health and hospital personnel for several reasons such as difficulty of confirming the existence of an outbreak, difficulty of determining source. Although many resources exist to guide patient notification about healthcare incidents (eg, bloodborne exposures, disease outbreaks), IMI clusters involve special considerations related to the complex diseases, uncertain exposures, and differential benefits and risks of notification. Early, nuanced communication about hospital-associated IMI clusters is almost always the best course of action to help reduce risks to patients' health and foster trust between patients and hospitals.

Contact Effect of a Methylobacterium sp. Extract on Biofilm of a Mycobacterium chimaera Strain Isolated from a 3T Heater-Cooler System

Mycobacterium chimaera is an opportunistic slowly growing non-tuberculous mycobacteriumof increasing importance due to the outbreak of cases associated with contaminated 3T heater-cooler device (HCD) extracorporeal membrane oxygenator (ECMO). The aim of this study was to evaluate the effect of pre-treating a surface with a Methylobacterium sp. CECT 7180 extract to inhibit the M. chimaera ECMO biofilm as well as of the treatment after different dehydration times. Surface adherence, biofilm formation and treatment effect were evaluated by estimating colony-forming units (CFU) per square centimeter and characterizing the amount of covered surface area, thickness, cell viability, and presence of intrinsic autofluorescence at different times using confocal laser scanning microscopy and image analysis. We found that exposing a surface to the Methylobacterium sp. CECT 7180 extract inhibited M. chimaera ECMO biofilm development. This effect could be result of the effect of Methylobacterium proteins, such as DNaK, trigger factor, and xanthine oxidase. In conclusion, exposing a surface to the Methylobacteriumsp. extract inhibits M. chimaera ECMO biofilm development. Furthermore, this extract could be used as a pre-treatment prior to disinfection protocols for equipment contaminated with mycobacteria after dehydration for at least 96 h.

International Society of Cardiovascular Infectious Diseases Guidelines for the Diagnosis, Treatment and Prevention of Disseminated Mycobacterium chimaera Infection Following Cardiac Surgery with Cardiopulmonary Bypass

Mycobacterial infection-related morbidity and mortality in patients following cardiopulmonary bypass surgery is high and there is a growing need for a consensus-based expert opinion to provide international guidance for diagnosing, preventing and treating in these patients. In this document the International Society for Cardiovascular Infectious Diseases (ISCVID) covers aspects of prevention (field of hospital epidemiology), clinical management (infectious disease specialists, cardiac surgeons, ophthalmologists, others), laboratory diagnostics (microbiologists, molecular diagnostics), device management (perfusionists, cardiac surgeons) and public health aspects.

Mycobacterium chimaera infections following cardiac surgery in Treviso Hospital, Italy, from 2016 to 2019: Cases report

BACKGROUND

An epidemic of Mycobacterium chimaera (M. chimaera) infections following cardiac surgery is ongoing worldwide. The outbreak was first discovered in 2011, and it has been traced to a point source contamination of the LivaNova 3T heater-cooler unit, which is used also in Italy. International data are advocated to clarify the spectrum of clinical features of the disease as well as treatment options and outcome. We report a series of M. chimaera infections diagnosed in Treviso Hospital, including the first cases notified in Italy in 2016.

CASE SUMMARY

Since June 2016, we diagnosed a M. chimaera infection in nine patient who had undergone cardiac valve surgery between February 2011 and November 2016. The time between cardiac surgery and developing symptoms ranged from 6 to 97 mo. Unexplained fever, psychophysical decay, weight loss, and neurological symptoms were common complaints. The median duration of symptoms was 32 wk, and the longest was almost two years. A new cardiac murmur, splenomegaly, choroidoretinitis, anaemia or lymphopenia, abnormal liver function tests and hyponatremia were common findings. All the patients presented a prosthetic valve endocarditis, frequently associated to an ascending aortic pseudoneurysm or spondylodiscitis. M. chimaera was cultured from blood, bioprosthetic tissue, pericardial abscess, vertebral tissue, and bone marrow. Mortality is high in our series, reflecting the poor outcome observed in other reports. Three patients have undergone repeat cardiac surgery. Five patients are being treated with a targeted multidrug antimycobacterial regimen.

CONCLUSION

Patients who have undergone cardiac surgery in Italy and presenting with signs and symptoms of endocarditis must be tested for M. chimaera.