Chimaera Infection Research Articles

Case report of the first cured patient with Mycobacterium Chimaera infection following cardiac valve replacement in the mainland of China

BackgroundMycobacterium chimaera infections subsequent to cardiac surgery are related to contaminated heater-cooler devices, with high mortality. Nevertheless, few studies have been reported in Asia.Case presentationWe described the case of a 55-year-old man with Mycobacterium chimaera infection following cardiac surgery in the mainland of China. He was diagnosed with endocarditis caused by Mycobacterium chimaera subsequent to open heart surgery. Metagenomic next-generation sequencing (mNGS) and 16S rRNA gene PCR analysis were used to identify potential pathogens. The patient underwent redo valve replacement surgery and received combination therapy with azithromycin, ethambutol, linezolid, and amikacin. No signs of relapse were observed during the 11-month follow-up visit.ConclusionsThis is the first documented case of Mycobacterium chimaera infection following cardiac surgery in the mainland of China and the first documented transnational imported case worldwide. Moreover, mNGS is a novel diagnostic technology that can guide antimicrobial therapy prior to obtaining fluid/tissue culture results for Mycobacterium chimaera, providing a new approach for the detection of potential Mycobacterium chimaera infection.

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

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. 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. 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. 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.

Coordinated, Collaborative Management of an Outbreak: Lessons for Maintenance of Patient Trust

One of the tenets of a successful provider-patient relationship is trust, and trust can only be maintained with bidirectional open and honest communication. This is especially true in communicating possible untoward outcomes of our surgeries. In this issue of The Annals of Thoracic Surgery, the article by Chandrasekar and colleagues1 shares the experience of one of the largest pediatric cardiac surgery centers in the United States with the outbreak of the Mycobacterium chimaera infection in cardiac surgical patients.

Long-Term Clinical and Multimodal Imaging Findings in Patients with Disseminated Mycobacterium Chimaera Infection.

Background: To analyze long-term ophthalmic clinical and multimodal imaging findings of disseminated Mycobacterium (M.) chimaera infection after cardiothoracic surgery among the Swiss Cohort. Methods: Systemic and multimodal ophthalmic imaging and clinical findings including rate of recurrence were reviewed and correlated to a previously proposed classification system of choroidal lesions and classification of ocular disease. Main Outcomes Measures: long-term clinical and multimodal ocular imaging findings of M. chimaera. Results: Twelve patients suffering from systemic infection from M. chimaera were included. Mean age at the first ophthalmic examination was 59 years (range from 48 to 66 years). Mean duration of the follow-up was 22.63 ± 17.8 months. All patients presented with bilateral chorioretinal lesions at baseline; 5 patients had additional signs, including optic disc swelling (2), choroidal neovascularization (1), retinal neovascularization (1) and cilioretinal vascular occlusion (1). Four recurrence events after discontinuation or adjustment of the antibiotic treatment were observed. Progressive choroiditis was seen in 5 patients under treatment, 4 of them deceased. Conclusions: Expertise from ophthalmologists is not only relevant but also critical for the assessment of the adverse drug effect of antimycobacterial treatment along with monitoring therapeutic response and identifying recurrences.

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

BackgroundIn 2012, a global outbreak of invasive Mycobacterium chimaera (M. chimaera) infection was identified in patients after cardiopulmonary bypass surgery. Investigations revealed the source to be heater-cooler unit (HCU) exhaust, with point-source contamination discovered at the LivaNova HCU manufacturing plant (London, UK). We report our experience with affected HCUs at a high-volume pediatric cardiac surgery center in the United States. MethodsA multidisciplinary 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 laboratory/culture data and infectious diseases consultation. ResultsCardiopulmonary bypass surgeries were performed in 4276 patients (median age: 2.1 years; range: 0-48.4 years) between October 2010 and October 2016. Call center volume was highest in the first 6 weeks after 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 computed tomography (n = 2), cardiac magnetic resonance imaging (n = 1), and pulmonary computed tomography (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. ConclusionsThrough a highly coordinated outreach effort, no patients have been found to have M. chimaera infection in the 6 years after exposure to contaminated HCUs. Ongoing vigilance for cases that may yet manifest is needed.

Updated Experience of Mycobacterium chimaera Infection: Diagnosis and Management in a Tertiary Care Center.

BackgroundDespite safety communications from the Food and Drug Administration (FDA) regarding the outbreak of Mycobacterium chimaera infections (MCIs) from contaminated heater-cooler devices, new cases continue to be identified.MethodsWe retrospectively reviewed confirmed cases of MCI that were managed at Mayo Clinic sites (Arizona, Florida, and Minnesota) from 09/2015 to 01/2021. Clinical histories including prior cardiovascular surgery were recorded. Diagnostic workup including ophthalmologic examination, imaging, and laboratory testing was reviewed. Treatment and survival outcomes on follow-up were obtained.ResultsTwelve patients with MCI were included. All patients had aortic valve or graft replacement. Five patients had their surgical procedures following the 10/15/2015 FDA safety communication. The mean time from surgery to symptom onset (range) was 32 (13–73) months. Ten of 11 patients who underwent ophthalmologic examination had chorioretinal abnormalities. Three patients who underwent microbial cell-free deoxyribonucleic acid sequencing tested positive for M. chimaera, which was subsequently confirmed with blood culture growth. Echocardiography and positron emission tomography/computed tomography (PET/CT) revealed evidence of prosthetic valve/graft infection in 7/12 (58.3%) and 6/10 (60.0%) of cases, respectively. Seven patients (58.3%) underwent redo cardiovascular surgery. Of these, 1 patient died 2 days postdischarge, 1 experienced spinal osteomyelitis relapse, and another had interval prosthetic valve fluorodeoxyglucose (FDG) uptake on PET/CT suspicious for recurrent infection. Among 4 patients on medical therapy only, 3 expired or transitioned to hospice during follow-up.ConclusionsMCI continues to occur despite the FDA communications. Incorporation of ophthalmologic examination and use of advanced tools may improve MCI diagnosis. The mortality in these patients is high even with aggressive surgical/medical management.

Mycobacterium chimaera: a report of 2 new cases and literature review

Mycobacterium chimaera is a non-tuberculous mycobacterium, member of the Mycobacterium avium complex (MAC), which has become a global public health concern due to infection following cardiac surgery performed with contaminated heater-cooler units. M. chimaera infection is characterized by a long latency, non-specific signs and symptoms and high mortality rates. Thus, the diagnosis is still challenging both for forensic pathologists and for clinicians. Clinical manifestations of M. chimaera infection include endocarditis, hepatitis, nephritis, encephalitis and chorioretinitis. A constant histopathologic finding is the presence of non-caseating granulomas, with multinucleated giant cells and histiocytes. Hereby, we present two cases of fatal disseminated M. chimaera infection following aortic valve surgery reporting clinical history and post-mortem findings. Further, we provide a brief overview of the literature with a special focus on histopathological characteristics of M. chimaera infection. The aim of this article is to provide a complete synopsis of histopathological characteristics useful for forensic pathologists.

Mycobacterium chimaera Genomics With Regard to Epidemiological and Clinical Investigations Conducted for an Open Chest Postsurgical Mycobacterium chimaera Infection Outbreak.

BackgroundPostsurgical infections due to Mycobacterium chimaera appeared as a novel nosocomial threat in 2015, with a worldwide outbreak due to contaminated heater-cooler units used in open chest surgery. We report the results of investigations conducted in France including whole-genome sequencing comparison of patient and heater-cooler unit isolates.MethodsWe sought M. chimaera infection cases from 2010 onwards through national epidemiological investigations in health care facilities performing cardiopulmonary bypass, together with a survey on good practices and systematic heater-cooler unit microbial analyses. Clinical and heater-cooler unit isolates were subjected to whole-genome sequencing analyzed with regard to the reference outbreak strain Zuerich-1.ResultsOnly 2 clinical cases were shown to be related to the outbreak, although 23% (41/175) of heater-cooler units were declared positive for M. avium complex. Specific measures to prevent infection were applied in 89% (50/56) of health care facilities, although only 14% (8/56) of them followed the manufacturer maintenance recommendations. Whole-genome sequencing comparison showed that the clinical isolates and 72% (26/36) of heater-cooler unit isolates belonged to the epidemic cluster. Within clinical isolates, 5–9 nonsynonymous single nucleotide polymorphisms were observed, among which an in vivo mutation in a putative efflux pump gene was observed in a clinical isolate obtained for 1 patient on antimicrobial treatment.ConclusionsCases of postsurgical M. chimaera infections have been declared to be rare in France, although heater-cooler units were contaminated, as in other countries. Genomic analyses confirmed the connection to the outbreak and identified specific single nucleotide polymorphisms, including 1 suggesting fitness evolution in vivo.

Mycobacterium chimaera genomics with regard to epidemiological and clinical investigations conducted for the open-chest post-surgical Mycobacterium chimaera infections outbreak

Post-surgical infections due to Mycobacterium chimaera appeared as a novel nosocomial threat in 2015, with a worldwide outbreak due to contaminated heater-cooler units used in open chest surgery. We report the results of investigations conducted in France including whole genome sequencing comparison of patient and HCU isolates. Methods We sought M. chimaera infection cases from 2010 onwards through national epidemiological investigations in healthcare facilities performing cardiopulmonary bypass together with a survey on good practices and systematic heater-cooler unit microbial analyses. Clinical and HCU isolates were subjected to whole genome sequencing analyzed with regards to the reference outbreak strain Zuerich-1. Results Only two clinical cases were shown to be related to the outbreak, although 23% (41/175) heater-cooler units were declared positive for M. avium complex. Specific measures to prevent infection were applied in 89% (50/56) healthcare facilities although only 14% (8/56) of them followed the manufacturer maintenance recommendations. Whole genome sequencing comparison showed that the clinical isolates and 72% (26/36) of heater-cooler unit isolates belonged to the epidemic cluster. Within clinical isolates, 5 to 9 non-synonymous single nucleotide polymorphisms were observed, among which an in vivo mutation in a putative efflux pump gene observed in a clinical isolate obtained for one patient under antimicrobial treatment. Conclusions Cases of post-surgical M. chimaera infections were declared to be rare in France, although heater-cooler units were contaminated as in other countries. Genomic analyses confirmed the connection to the outbreak and identified specific single nucleotide polymorphisms, including one suggesting fitness evolution in vivo.

Ocular manifestations of disseminated Mycobacterium chimaera infection after cardiothoracic surgery

ObjectiveTo describe the ocular manifestations of disseminated Mycobacterium chimaera infection after cardiothoracic surgery. DesignRetrospective, observational case series. ParticipantsPatients with disseminated M. chimaera infection treated at the University of Alberta Hospital and Royal Alexandra Hospital in Edmonton, Alberta, Canada. MethodsSeven patients (14 eyes) with systemic M. chimaera infection after aortic graft and/or valvular surgeries were reviewed for ocular involvement. Cases were identified based on histopathologic analysis of cardiac tissue, repeat positive mycobacterial blood cultures, and cerebrospinal fluid analysis. Clinical ocular findings, fundus autofluorescence, fluorescein angiography, spectral-domain optical coherence tomography (SD-OCT), and autopsy results are described. ResultsThe mean age of our patients was 63 years (range, 22–76 years). Aortic graft and/or valvular surgeries were performed between June 2015 and April 2016. The mean duration from surgery to diagnosis of infection was 27 months (range, 19–36 months). All patients exhibited white-yellowish choroidal lesions. Bilateral, multifocal choroiditis was observed in 6 patients (12 eyes), who died of disseminated M. chimaera infection despite aggressive, multiagent antimicrobial therapy. One patient had a solitary, white-yellow choroidal lesion in the left eye only. Choroidal lesions were hyperfluorescent on late-phase fluorescein angiography and corresponded to localized choroidal thickening and retinal elevation on SD-OCT. ConclusionsM. chimaera infection after cardiothoracic surgery can cause life-threatening disease involving multiple organ systems. Ocular involvement is an important and possibly early clinical finding, with good correlation to systemic disease severity. Ophthalmological assessment and multimodal imaging may aid in early diagnosis and can be used to monitor disease progression.

Lower Recovery of Nontuberculous Mycobacteria from Outdoor Hawai'i Environmental Water Biofilms Compared to Indoor Samples.

Nontuberculous mycobacteria (NTM) are environmental organisms that can cause opportunistic pulmonary disease with species diversity showing significant regional variation. In the United States, Hawai’i shows the highest rate of NTM pulmonary disease. The need for improved understanding of NTM reservoirs led us to identify NTM from patient respiratory specimens and compare NTM diversity between outdoor and indoor locations in Hawai’i. A total of 545 water biofilm samples were collected from 357 unique locations across Kaua’i (n = 51), O’ahu (n = 202), Maui (n = 159), and Hawai’i Island (n = 133) and divided into outdoor (n = 179) or indoor (n = 366) categories. rpoB sequence analysis was used to determine NTM species and predictive modeling applied to develop NTM risk maps based on geographic characteristics between environments. M. chimaera was frequently identified from respiratory and environmental samples followed by M. chelonae and M. abscessus; yet significantly less NTM were consistently recovered from outdoor compared to indoor biofilms, as exemplified by showerhead biofilm samples. While the frequency of M. chimaera recovery was comparable between outdoor and indoor showerhead biofilms, phylogenetic analyses demonstrate similar rpoB gene sequences between all showerhead and respiratory M. chimaera isolates, supporting outdoor and indoor environments as possible sources for pulmonary M. chimaera infections.

870. Mycobacterium chimaera Outbreak: Infection Control and Clinical Experiences in Edmonton, Alberta

Background Mycobacterium chimaera is responsible for a global outbreak due to contaminated heater-cooler units (HCUs) used in cardiothoracic surgery and has been associated with high mortality. Optimal treatment is not known. The objectives of this study were to describe the Infection Control strategies utilized by the University of Alberta hospital and Mazankowski Heart Institute (MAZ) prior to availability of new HCUs, and outline the clinical course of locally acquired M. chimaera infection.MethodsWe reviewed interventions undertaken to mitigate the risk of M. chimaera infection. Any MAZ patient with M. chimaera isolated at an anatomic site with a history of cardiothoracic surgery from 2012-present were identified. Charts were reviewed for patient and infection characteristics.ResultsAll manufacturer’s instructions for HCU cleaning-disinfection were followed. The MAZ was compliant with CDC recommendations for directing HCU ventilation exhaust away from the surgical field and to the use of filtered water. M. chimaera was isolated in 3/8 local HCUs. After decontamination procedure, 1 HCU grew M. chimaera but cleared after a second attempt. Smoke studies demonstrated aerosolization of HCU exhaust in October 2016 therefore the laminar air curtains were manipulated for increased flow in October and November 2016. By June 2017, HCUs were retro-fitted and in late 2017 all pre-2014 Sorin HCUs were replaced.10 patients have been diagnosed with M. chimaera infection post-cardiothoracic surgery performed at the MAZ. None occurred after manipulation of the laminar air curtain. Mean patient age at time of cardiothoracic surgery was 62.3 years and 6 were male. All had implantation of prosthetic material. The most common culture-positive sites were blood in 9/10, urine in 5/10 and prosthetic material or surgical site in 3/10. 6/10 have died due to infection and mean life expectancy of those deceased from first positive culture is 123 days. An additional survivor has been transitioned to comfort care and lost to follow-up.Conclusion M. chimaera post cardiothoracic surgery has been challenging from an infection control perspective but the risk appears to have been mitigated through manipulation of the laminar air curtain. Locally, M. chimaera has been associated with significant (60%) mortality.Disclosures All Authors: No reported disclosures

PCV59 Economic Burden Associated with the Management of Mycobacterium Quimaera Endocarditis from the Perspective of a Spanish Hospital

Mycobacterium Chimaera (M.Chimaera) is a highly resistant microorganism responsible for the development of severe infections in patients undergoing cardiothoracic surgeries with extracorporeal circulation. Infections become clinically apparent after a time lag of months to years and lead to significant mortality and morbidity. Recommended treatment includes a combination of multiple antimicrobial drugs and the removal of foreign material. The aim of this study was to determine the cost associated with the management of a M.Chimaera endocarditis from a Spanish hospital perspective. A cost analysis was developed based on previously published results on health resource use (HRU) of the management of a prosthetic infective endocarditis. Unit costs were applied to estimates of HRU comprising diagnostic tests, hospital length of stay and pharmacological treatment. Costs were obtained from different Spanish sources and expressed in €2020. Deterministic sensitivity analysis was performed to assess the robustness of the base case results. The mean cost of the management of a M. Chimaera infection was €93,470.68 (€84,123.61- €102,817.75). Inpatient length of stay (121 days) represented the major cost driver (€77,936.79; 83.4%) followed by the pharmacological treatment (€5,058.99; 5.4%) and the aortic valve replacement surgery (€4,59.49; 4.9%), respectively. M. Chimaera associated infections represent a relevant economic burden for the hospitals. Current prevention strategies such as heater-cooler units disinfection protocols, and equipment removal from the operating room have clinically demonstrated to be insufficient and costly. Innovative machines such us non-toxic glycol based HCUs should be taken into consideration due to its proven long-term bactericidal properties in order to avoid potential infections in patients undergoing chest surgeries.

Abstract 14789: Multimodality Imaging in Mycobacterium Chimaera Cardiovascular Infections

Introduction: Mycobacterium Chimaera (MC) infections following cardiovascular surgery are challenging to diagnose given their insidious presentation. We therefore reviewed the various imaging modalities used to diagnose these infections at Mayo Clinic. Methods: Cases from 01/01/2010-06/01/2020 were identified using electronic medical records. Demographics and clinical history were collected. Imaging studies, including transthoracic echocardiogram (TTE), transesophageal echocardiogram (TEE), positron emission tomography / computed tomography (PET/CT), cardiac CT (CCT), and cardiac magnetic resonance (CMR) were reviewed. Results: A total of 7 patients (85.7% male) were found. 6 underwent aortic valve replacement and 1 received an aortic composite valve conduit. Surgical dates ranged from 01/2010-12/2018. Mean age at presentation was 63.3 years. Mean time from surgery to symptom onset was 28.0 months. All patients underwent TTE and TEE; prosthetic valve endocarditis was identified in 6 cases between both, while CMR established the diagnosis in 1 case. TTE showed prosthetic valve obstruction in 2 cases and an anterior pseudoaneurysm in 1 case. TEE findings included thickened prosthesis and/or vegetations (n=5), thickened posterior root (n=4), and root abscess (n=3). Among the 3 patients who underwent PET/CT, 2 demonstrated increased fluorodeoxyglucose (FDG) uptake around the aortic prosthesis; in addition, 1 had elevated FDG uptake in the myocardium suggesting myocarditis. 1 patient did not have aortic prosthesis FDG uptake. In the 2 patients who had CCT, 1 showed a pseudoaneurysm that prompted suspicion for endocarditis, and the other revealed a fluid collection adjacent to the aortic valve conduit. 2 patients underwent CMR; 1 had aortic prosthesis thickening and patchy areas of myocardial delayed enhancement suspicious for myocarditis, whereas the other showed vegetation and an aortic root abscess. Conclusion: TTE plus TEE successfully identified MC prosthetic valve endocarditis in most cases with TEE having higher specificity. Advanced imaging techniques are helpful to support the diagnosis and assess for myocardial and/or aortic involvement. Combining these modalities is therefore crucial in unveiling this elusive organism.

Successful termination of an outbreak of Mycobacterium chimaera infections associated with contaminated heater-cooler devices.

The global outbreak of invasive Mycobacterium chimaera infections associated with heater-cooler devices (HCDs) presented several important and unique challenges. To mitigate the risk of infection, we removed the HCDs from operating rooms (ORs) at our hospital and since that time (4.5 years ago) we have had no new cases.

Use of a Biological Tracer to Investigate Microbial Aerosols Generated by Heater-Cooler Units

Background: A multinational outbreak of Mycobacterium chimaera endocarditis following cardiac surgery has been attributed to the use of heater-cooler units (HCUs) during cardiopulmonary bypass. It is hypothesized that mycobacteria can be transmitted to the surgical site via the aerosolization of contaminated water from within the unit. In the United Kingdom, M. chimaera infections have been linked to 1 specific make and model of HCU, which was shown to generate microbial aerosols when circulating water. The manufacturer has since modified this HCU and claims that the dispersal of aerosols has now been prevented. M. chimaera is a common contaminant of HCUs, regardless of make, model, and manufacturer. To help inform local decision making, hospitals require evidence that this modified HCU and/or alternative heater-cooler systems can reduce the risk of mycobacterial infection by incorporating design features that prevent the generation of microbial aerosols external to the device. The time required to culture M. chimaera means investigations focusing on naturally or artificially contaminated HCUs are problematic. Instead, specialist aerobiological techniques incorporating a nonpathogenic, aerostable, biological tracer (Bacillus atrophaeus) were used to investigate microbial aerosols generated and released from brand-new and ‘upgraded’ HCUs. Methods: 4 HCUs (A–D), supplied directly by the manufacturers, were filled with filtered tap water, and high numbers of B. atrophaeus (109 CFU/L) were added to the tanks. High-volume cyclone samplers were used to sample the air when each HCU was switched off and during different operational phases. Samplers were operated for 5 minutes and the collecting fluid cultured for B. atrophaeus. The number of colonies was converted to CFU per cubic meter of air. Results: Under controlled experimental conditions, HCU-A released a small but significant level of aerosol during operational phases (eg, cooling) that resulted in increased pressure within the tank. The filler flap was identified as the principal area of aerosol release. The circulation of water within HCU-B and HCU-C was shown to generate an aerosol but, when connected to an ‘aerosol collection set,’ this aerosol was not released. However, it is essential that effective and sufficient vacuum is maintained. There was no aerosol release from HCU-D. Conclusions: A specialist in aerobiology using a biological tracer can determine the level of aerosol released from an HCU and its location. However, transmission of M. chimaera could occur via aerosolization of contaminated water, but it is not the only possible route of infection. The efficacy of recommended decontamination procedures must also be assured.Funding: NoneDisclosures: None

Genomic analysis of cardiac surgery-associated Mycobacterium chimaera infections in Italy.

One hundred and twenty-two Mycobacterium chimaera strains isolated in Italy from cardiac surgery-related patients, cardiac surgery-unrelated patients and from heater-cooler units, were submitted to whole-genome sequencing and to subsequent SNP analysis. All but one strains isolated from cardiac surgery-related patients belonged to Subgroup 1.1 (19/23) or Subgroup 1.8 (3/23). Only 28 out of 79 strains isolated from heater-cooler units belonged to groupings other than 1.1 and 1.8. The strains isolated from cardiac surgery-unrelated patients were instead distributed across the phylogenetic tree. Our data, the first on isolates from Italy, are in agreement with a recent large genomic study suggesting a common source, represented by strains belonging to Subgroups 1.1 and 1.8, of cardiac surgery-related Mycobacterium chimaera infections. The strains belonging to groupings other than 1.1 and 1.8 isolated from heather-cooler units evidently resulted from contaminations at hospital level and had no share in the Mycobacterium chimaera outbreak. One Mycobacterium chimaera strain investigated in this study proved distant from every previously known Mycobacterium chimaera Groups (1, 2, 3 and 4) and we propose to assign to a novel group, named "Group 5".

Mycobacterium chimaera in heater–cooler devices: an experience in a tertiary hospital in Spain

The aim of the study was to describe the Mycobacterium chimaera contamination in heater–cooler devices after the application of a protocol of cleaning and disinfection in a tertiary hospital. It was an observational study at the La Paz-Cantoblanco-Carlos III University Hospital, Madrid, Spain. Seven heater–cooler devices are used in our hospital: five 3T Sorin (LivaNova) and two Maquet. We followed the manufacturers' instructions for cleaning and disinfection of the different heater–cooler devices. Environmental testing was developed monthly from January 2017 to July 2019. Samples were obtained from both cardioplegia and patient circuits and before and after the disinfection process and were cultured in appropriate media for non-tuberculous mycobacteria and heterotrophic bacteria (coliforms and Pseudomonas aeruginosa). A total of 320 samples were taken. Mycobacterium chimaera grew in four water samples (1.25%) from three different heater–cooler devices, with two positive results occurring after disinfection. The heterotrophic bacteria Delftia acidovorans and Stenotrophomonas maltophilia were also found. There has not been a case of M. chimaera infection in patients after cardiac surgery in our hospital. In March 2019, we decided to move the heater–cooler device outside the operating room. Mycobacterium chimaera contamination is not always eradicated by disinfection processes. We believe that placing 3T heater–cooler devices outside the operating room is the best option in preventing M. chimaera infection during cardiac surgery.

Surveillance and control of M. chimaera infections in the Tuscany Region, Italy

Abstract Background Disseminated M. chimaera infections among patients who underwent open-chest surgery with cardiopulmonary bypass have been associated with the contamination of heater-cooler devices (HCDs). The Tuscany region in the Decree 3822/2019 issued recommendations for the surveillance and control of M. chimaera infections. Methods In three Tuscan cardiac surgery centers, the case finding was carried out through evaluation and testing of patients with a history of HCD exposure (past 6 years) was performed. Water and aerosol samples were analyzed from each HCDs to determine the microbiological parameters required by the Directive 98/83/CE and to assess the presence of non-tuberculous mycobacteria (NTMs), according to the regional protocol. Results M. chimaera infection was not found in any patient and all clinical specimens tested negative. 22 HCDs were sampled (n.12 LivaNova, n.1 Terumo and n.9 Maquet) for a total of 114 samples (45, 8, 2 and 59 respectively). All the microbiological parameters were compliant, excepted for total microbial count at 36 °C that exceeded 100 CFU/ml in 50% (57/114) of samples and for the presence of P.aeruginosa in 10% (12/114). NTMs were detected in 16% (18/114) of HCDs: M. chimaera was identified in 11% (13/114) of samples and in 4% (5/114) M. gordonae. All aerosol samples were negative for NTMs, but in the HCDs Maquet, B.cereus were detected in 7% (4/59) of the samples, K.oxytoca in 2% (1/59), B.ursincola in 2% (1/59) and S. paucimobilis in 3% (2/59). Only S. paucimobilis was isolated also in the same HCD water sample. Conclusions The implementation of maintenance and disinfection procedures of HCDs was able to reduce the risk of contamination and aerosolization by NTMs but not of other microorganisms. Key messages Further strategies should be put in place for the cases finding. Moreover, reliable decontamination and identification of agents that can disrupt biofilms and increase chlorine susceptibility of mycobacteria are required.

A Mycobacterium chimaera infection after 12 years since cardiac surgery: a case report

Abstract Issues Mycobacterium chimaera bacterium, firstly identified in 2004, is mainly present in drinking water but is generally not harmful for human health. Incubation period ranges from 3 to 72 months, with a median of 17 months. Clinical signs are fever, weakness and weight loss. The infection has a lethality rate of 50%. Invasive infections are associated to the use of Heater-Cooler-Devices (HCD) in cardiovascular surgery. Description of the Problem This work reports on an unexpected Mycobacterium chimaera infection case occurred after a time period much longer than what literature reports for both incubation and surgical infection. In January 2007, a 67-year-old man underwent cardiac surgery for an aortic dissection Stanford type A, with implantation of an ascending aorta prosthesis at Udine Academic Hospital (Italy). After a chronic heart failure relapse occurred in September 2018, he developed fever of unknown origins, sepsis, and then he underwent surgery to substitute the vascular prothesis. In January 2019 the clinical condition of the patient got worse and he died in September 2019. Results The first level bacterial culture turned out to be positive for Mycobacteria, so the second level molecular biology test was carried out with GenoType NTM-DR. This analysis revealed a specific positivity for Mycobacterium chimaera. The confirmation test on the Heater-Cooler-Device (HCD) could not be carried out as this device was scrapped since years. Lessons This case report suggests that Mycobacterium chimaera incubation period can be extremely variable. Therefore, when performing differential diagnosis, it should be considered even for those patients who underwent cardiac surgery more than 5 years prior clinical manifestation. We suggest extending the current ECDC's exposure criteria, assuming that incubation period could cover the entire patient's life. Key messages Mycobacterium chimaera can have an incubation period much longer than what is usually described in literature and ECDC guidelines. This report can be considered a starting point to improve the hospital infection control surveillance system in hospitals performing cardiac surgery.