Clinical and genomic features of Mycobacterium avium complex: a multi-national European study.

BACKGROUND: The Mycobacterium avium complex (MAC) comprises the most frequent non-tuberculous mycobacteria (NTM) in Central Europe and currently includes twelve species. M. avium (MAV), M. intracellulare subsp. intracellulare (MINT), and M. intracellulare subsp. chimaera (MCH) are clinically most relevant. However, the population structure and genomic landscape of MAC linked with potential pathobiological differences remain little investigated. METHODS: Whole genome sequencing (WGS) was performed on a multi-national set of MAC isolates from Germany, France, and Switzerland. Phylogenetic analysis was conducted, as well as plasmids, resistance, and virulence genes predicted from WGS data. Data was set into a global context with publicly available sequences. Finally, detailed clinical characteristics were associated with genomic data in a subset of the cohort. RESULTS: Overall, 610 isolates from 465 patients were included. The majority could be assigned to MAV (n = 386), MCH (n = 111), and MINT (n = 77). We demonstrate clustering with less than 12 SNPs distance of isolates obtained from different patients in all major MAC species and the identification of trans-European or even trans-continental clusters when set into relation with 1307 public sequences. However, none of our MCH isolates clustered closely with the heater-cooler unit outbreak strain Zuerich-1. Known plasmids were detected in MAV (325/1076, 30.2%), MINT (62/327, 19.0%), and almost all MCH-isolates (457/463, 98.7%). Predicted resistance to aminoglycosides or macrolides was rare. Overall, there was no direct link between phylogenomic grouping and clinical manifestations, but MCH and MINT were rarely found in patients with extra-pulmonary disease (OR 0.12 95% CI 0.04-0.28, p < 0.001 and OR 0.11 95% CI 0.02-0.4, p = 0.004, respectively) and MCH was negatively associated with fulfillment of the ATS criteria when isolated from respiratory samples (OR 0.28 95% CI 0.09-0.7, p = 0.011). With 14 out of 43 patients with available serial isolates, co-infections or co-colonizations with different strains or even species of the MAC were frequent (32.6%). CONCLUSIONS: This study demonstrates clustering and the presence of plasmids in a large proportion of MAC isolates in Europe and in a global context. Future studies need to urgently define potential ways of transmission of MAC isolates and the potential involvement of plasmids in virulence.

Recurrent Choroidal Neovascular Membrane as the Initial Presentation of Mycobacterium chimaera-Associated Serpiginoid Choroiditis.

PURPOSE: To report a rare presentation of a proven case of Mycobacterium chimaera infection presenting as multifocal choroiditis with recurrent choroidal neovascular membrane (CNVM) in one eye, initially misdiagnosed as punctate inner choroidopathy and later developed serpiginous-like choroiditis in the other eye. METHODS: Retrospective case report with a review of existing literature. RESULTS: A 30-year-old women presented with metamorphopsia (OD) and best-corrected visual acuity (BCVA) of 6/24 (OD) and was diagnosed to have punctate inner choroidopathy with CNVM (OD). Since then, she had received four intravitreal anti-vascular endothelial growth factor injections over 3 years. Two years later, she developed a slowly progressing choroidal lesion radiating from the disc in a serpiginoid manner in the left eye. There was no vitritis. Labs revealed a positive QuantiFERON-TB Gold test. High-resolution computed tomography of the thorax showed sub-centimetre noncalcified lymph nodes in subcarinal and perivascular regions, minimal pleural thickening in left lower zone, minimal pericardial effusion, bronchiectatic changes, and fibrotic strands in right middle and left lower lobes. Bronchoalveolar lavage grew M. chimaera intracellularae (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry). She was given a course of clarithromycin, moxifloxacin, rifampicin, and doxycycline for 12 months. Though the right eye remained stable, choroidal lesion in the left eye continued to progress threatening the fovea, requiring oral steroids, methotrexate, and an intravitreal dexamethasone implant. At the last follow-up, her BCVA was 6/18 (OD) and 6/6 (OS). Both eyes were stable. CONCLUSION: This case highlights a rare presentation of proven M. chimaera infection presenting as multifocal choroiditis with recurrent CNVM in one eye and serpiginous-like choroiditis in the other eye, requiring aggressive treatment to salvage the vision.

Disseminated Mycobacterium chimaera infection successfully treated with a clofazimine-containing regimen and long-term follow-up after discontinuing treatment.

Mycobacterium chimaera is a slow-growing member of the Mycobacterium avium complex. It can contaminate tap water and has been detected in water tanks of heater-cooler devices used during open-heart surgery. Herein we report a case of a 67-year-old- male with disseminated M. chimaera infection who presented with fevers, significant weight loss and was found to have bacteremia with prosthetic valve endocarditis, chorioretinitis, bone marrow and splenic granulomas two years after an open-heart surgery. He developed multiple drug adverse events over the course of treatment but was successfully treated using a clofazimine containing regimen along with aortic valve replacement. He has remained symptom-free with no signs of recurrence three years after completion of antimicrobials. Clofazimine is an effective alternative that can be used as part of a multi-drug regimen in M. chimaera infection when there is resistance to first-line drugs or when adverse drug reactions occur.

Biofilm Development by Mycobacterium avium Complex Clinical Isolates: Effect of Clarithromycin in Ultrastructure.

BACKGROUND: The Mycobacterium avium complex includes the commonest non-tuberculous mycobacteria associated with human infections. These infections have been associated with the production of biofilms in many cases, but there are only a few studies about biofilms produced by the species included in this group. METHODS: Three collection strains (M. avium ATCC25291, M. intracellulare ATCC13950, and M. chimaera DSM756), three clinically significant strains (647, 657, and 655), and three clinically non-significant ones (717, 505, and 575) of each species were included. The clinical significance of the clinical isolates was established according to the internationally accepted criteria. The biofilm ultrastructure was studied by Confocal-Laser Scanning Microscopy by using BacLight Live-Dead and Nile Red stains. The viability, covered surface, height, and relative autofluorescence were measured in several images/strain. The effect of clarithromycin was studied by using the technique described by Muñoz-Egea et al. with modifications regarding incubation time. The study included clarithromycin in the culture medium at a concentration achievable in the lungs (11.3 mg/L), using one row of wells as the control without antibiotics. The bacterial viability inside the biofilm is expressed as a percentage of viable cells. The differences between the different parameters of the biofilm ultrastructure were analyzed by using the Kruskal-Wallis test. The correlation between bacterial viability in the biofilm and treatment time was evaluated by using Spearman's rank correlation coefficient (ρ). RESULTS: The strains showed differences between them with all the studied parameters, but neither a species-specific pattern nor a clinical-significance-specific pattern were detected. For the effect of clarithromycin, the viability of the bacteria contained in the biofilm was inversely proportional to the exposure time of the biofilm (ρ > -0.3; p-value < 0.05), excluding two M. chimaera strains (M. chimaera DSM756 and 575), which showed a weak positive correlation with treatment time (0.2 < ρ < 0.39; p-value < 0.05). Curiously, despite a clarithromycin treatment of 216 h, the percentage of the biofilm viability of the strains evaluated here was not less than 40% at best (M. avium 717). CONCLUSIONS: All the M. avium complex strains studied can form biofilm in vitro, but the ultrastructural characteristics between them suggest that these are strain-specific characteristics unrelated to the species or the clinical significance. The clarithromycin effect on MAC species is biofilm-age/time-of-treatment-dependent and appears to be strain-specific while being independent of the clinical significance of the strain.

Non-tuberculous mycobacteria lung disease due to Mycobacterium chimaera in a 67-year-old man treated with immune checkpoint inhibitors for lung adenocarcinoma: infection due to dysregulated immunity?

Immune checkpoint inhibitors (ICIs) are drugs growingly employed in cancer immunotherapy which have significantly improved the prognosis of several tumours. ICIs act by restoring the "exhausted" immune system and increasing the number of T cells active against pathogens losing tolerogenic signalling, which has been linked to an increased risk of infectious events. We present the case of a 67-year-old man with locally advanced lung adenocarcinoma treated with the anti-PD-L1 durvalumab. Three months after immunotherapy started, an apparent radiological progression was found with elements suggesting a parenchymal superinfection associated with weight loss, asthenia, and sputum emission. A bronchoalveolar lavage resulted positive for Mycobacterium chimaera, and treatment with amikacin iv (for eight weeks) and daily azithromycin, ethambutol, and rifampicin was started. Thirteen months after treatment started, the patient is alive with a stable lung condition. The case highlights the risk of non-tuberculous mycobacteria lung disease (NTM-LD) in patients receiving ICIs treatment. We hypothesise that durvalumab induced an exaggerated immune response toward the mycobacteria, leading to immunopathology and overt clinical manifestations. Clinicians should be aware of this possibility in patients receiving ICIs developing new signs/symptoms related to the respiratory tract, especially in countries with a high prevalence of NTM-LD.

Blind spot in endocarditis guidelines: Mycobacterium chimaera prosthetic valve endocarditis after cardiac surgery-a case series.

Background: The recently published 2023 Duke-ISCVID Criteria for Infective Endocarditis for the first time consider mycobacteria (esp. Mycobacterium chimaera) as 'typical' microorganisms for prosthetic valve endocarditis (major criteria). This reflects the ongoing worldwide outbreak of M. chimaera prosthetic valve endocarditis. Case summary: Our case series demonstrates a diagnostic pathway for mycobacterial endocarditis. Symptoms are unspecific, and standard microbiological testing does not result in identification of the causative agent (see Graphical Abstract); therefore patients require special microbiological and imaging diagnostics. One patient with early diagnosis and stringent antibiotic and surgical therapy survived. Two patients with disseminated infection at the time point of diagnosis had fatal outcomes. Discussion: The diagnostic approach in our small retrospective case series is in line with the new modified Duke criteria and underlines the diagnostic gap in the previous definitions. Outcome of M. chimaera prosthetic valve endocarditis is related to timely diagnosis and anti-mycobacterial as well as surgical treatment. Non-tuberculous mycobacteria should be given more attention in future endocarditis guidelines.

Immunological and metabolic characterization of environmental Mycobacterium chimaera infection in a murine model.

Mycobacterium chimaera causes pulmonary disease, but little is known of gradations in isolate virulence. Previously, 17 M. chimaera isolates were screened for survival in THP1 macrophages. "M. chimaera 1" was categorized as "more virulent" because it showed the greatest survival in macrophages, whereas "M. chimaera 2" was categorized as "less virulent" with reduced survival. Herein, we infected C3HeB/FeJ mice to compare the in vivo immune responses to M. chimaera 1 and 2. Unlike macrophages, significantly lower M. chimaera 1 counts were recovered from mouse lung tissue and BAL cells with less lung histopathologic changes compared to M. chimaera 2. Compared to M. chimaera 2, significantly more IL-1ß, IL-6, and TNFα was produced early after M. chimaera 1 infection. LC-MS metabolomics analyses of BAL fluid revealed divergence in sphingolipid, phospholipid metabolism between M. chimaera 1 versus M. chimaera 2 mice. From pan-GWAS analyses, virulence and organizing DNA/molecular structure genes were associated with more virulent M. chimaera isolates. Vigorous lung-specific immune responses to M. chimaera 1 may influence effective bacterial control, but for a different isolate M. chimaera 2, subvert immune control. Continued studies of the gradations in virulence among the same NTM species will advance our understanding of NTM pathogenesis.

Multiple mutations of Mycobacterium intracellulare subsp. chimaera causing false-negative reaction to the transcription-reverse transcription concerted method for pathogen detection.

OBJECTIVES: To report an isolate of Mycobacterium intracellulare subsp. chimaera with multiple mutations in 16S ribosomal RNA (rRNA) gene, resulting in the false-negative reaction to the transcription-reverse transcription concerted (TRC) method for Mycobacterium avium-intracellulare complex. METHODS: We used TRC, polymerase chain reaction (PCR), and Matrix-assisted laser desorption/ionization Time-of-Flight/Mass Spectrometry (MALDI-TOF/MS) methods to identify a clinical isolate in 2021. Due to the discordant results between TRC and PCR or MALDI-TOF MS methods, 16S rRNA sequencing, whole-genome shotgun (WGS) sequencing, and average nucleotide identity (ANI) analysis were employed to identify the isolate. RESULTS: A mycobacterial isolate from a sputum sample gave negative results for the detection of Mycobacterium tuberculosis complex or M. avium-intracellulare complex by the TRC method. However, the isolate was identified as M. intracellulare by both PCR method and MALDI-TOF MS method. WGS sequencing of 16S rRNA genome revealed eight substitution mutations and one insertion mutation within the region, which could hamper the correct reaction to TRC method. Subsequent ANI analysis between the isolate and various species of nontuberculosis mycobacteria revealed that the isolate could be identified as M. intracellulare subsp. chimaera. CONCLUSION: Rare mutations within the 16S rRNA genome resulted in the false-negative identification of Mycobacterium chimaera by the TRC method. WGS sequencing and ANI analysis was necessary to identify the isolate.

Clinical characteristics and outcome of Mycobacterium chimaera infections after cardiac surgery: systematic review and meta-analysis of 180 heater-cooler unit-associated cases.

OBJECTIVES: Since 2013, heater-cooler unit (HCU) associated Mycobacterium chimaera infections linked to a global outbreak have been described. These infections were characterised by high morbidity and mortality due to delayed diagnosis, as well as challenges in antimycobacterial and surgical therapy. This study aimed to investigate the clinical characteristics and outcome of published cases of HCU-associated M. chimaera infections. METHODS: We searched PubMed and the Web of Science until 15 June 2022 for case reports, case series, and cohort studies, without language restriction, on patients with M. chimaera infection and a prior history of cardiac surgery. In this systematic review of case reports, no risk of bias assessment could be performed. Clinical, microbiological, and radiological features were recorded. Logistic regression and time-to-event analyses were performed to identify the potential factors associated with better survival. RESULTS: One hundred eighty patients from 54 publications were included. Most patients underwent surgical aortic valve (67.0%; 118/176 of patients with available data) or combined aortic valve and root replacement (15.3%; 27/176). The median period between the time point of surgery and the first symptoms was 17 months (interquartile range 13-26 months). The overall case fatality rate was 45.5% (80/176), with a median survival of 24 months after the initiation of antimycobacterial therapy or diagnosis. A reoperation (including the removal or exchange of foreign material) was associated with better survival in multivariate logistic regression (OR 0.32 for lethal events; 95% CI 0.12-0.79; p 0.015) and in time-to-event analysis (p 0.0094). DISCUSSION: This systematic review and meta-analysis confirm the high overall mortality of HCU -associated disseminated M. chimaera infections after cardiac surgery. A reoperation seems to be associated with better survival. Physicians have to stay aware of this infection, as patients might still be present today due to the long latency period.

An Unusual Case of Hemophagocytic Lymphohistiocytosis Associated with Mycobacterium chimaera or Large-Cell Neuroendocrine Carcinoma.

Hemophagocytic lymphohistiocytosis (HLH) is a rare and very dangerous condition characterized by abnormal activation of the immune system, causing hemophagocytosis, inflammation, and potentially widespread organ damage. The primary (genetic) form, caused by mutations affecting lymphocyte cytotoxicity, is most commonly seen in children. Secondary HLH is commonly associated with infections, malignancies, and rheumatologic disorders. Most current information on diagnosis and treatment is based on pediatric populations. HLH is a disease that should be diagnosed and treated promptly, otherwise it is fatal. Treatment is directed at treating the triggering disorder, along with symptomatic treatment with dexamethasone and etoposide. We present a 56-year-old patient who was admitted with worsening weakness, exertional dyspnea, dry and nonproductive cough, and a 5-pound weight loss associated with loss of appetite. This is among the rare disorders that are not commonly encountered in day-to-day practice. Our differential diagnoses were broad, including infection, such as visceral leishmaniasis, atypical/tuberculous mycobacteria, histoplasmosis, Ehrlichia, Bartonella, Brucella, Adenovirus, disseminated herpes simplex virus (HSV), hematological-like Langerhans cell histiocytosis, or multicentric Castleman disease; drug reaction, such as drug rash with eosinophilia and systemic symptoms (DRESS); and metabolic disorder, including Wolman's disease (infantile lysosomal acid lipase deficiency) or Gaucher's disease. Based on our investigations as described in our case report, it was narrowed down to hemophagocytic lymphohistiocytosis and COVID-19. Two COVID-19 tests were negative. His lab abnormalities and diagnostic testing revealed hemophagocytic lymphohistiocytosis. He was empirically started on antibiotics and dexamethasone, to be continued for 2 weeks then tapered if the patient showed continued improvement. Dexamethasone was tapered over 8 weeks. He improved on just one of the Food and Drug Administration (FDA)-approved medications, proving that treatment should be tailored to the patient. In addition, in this case study, we included the background, etiology, pathogenesis, diagnosis, management, and prognosis of HLH.

Long-Term Follow-Up after Mycobacterium Chimaera Infection Following Cardiac Surgery: Single-Center Experience.

BACKGROUND: Disseminated Mycobacterium chimaera (M. chimaera) infection following cardiac surgery has been associated with a high mortality. The long-term impact of surgery and the appropriate surgical approach are still matters of debate. METHODS: From 2015 to 2019, seven patients with M. chimaera infection following cardiac surgery were isolated. RESULTS: The median incubation time was 30 months (IQR 18-38). Echocardiography was unremarkable in three patients (43%). We decided to redo cardiac surgery in all patients and explanted all previously implanted prosthetic material. All explant cultures yielded M. chimaera. One patient (14%) died in-hospital seven months after the redo surgery. After a median follow-up of 59.6 months (IQR 39.1-69.6), we observed three infection relapses among the survivors (43%), presumably due to concomitant extracardiac infection and recurrent cardiac implant infection. CONCLUSIONS: M. chimaera infection following cardiac surgery is associated with a delayed and unspecific clinical presentation. Echocardiogaphy has a limited sensitivity for prosthetic valve infection with M. chimaera, and negative findings should not preclude the surgical decision. The extraction of all previously implanted material is crucial to achieving the source control, as the re-implantation of prosthetic material as well as uncontrolled extracardiac infection at the time of the redo cardiac surgery appear to be key factors for persisting/relapsing infection.

Molecular Epidemiologic Investigation of Mycobacterium intracellulare Subspecies chimaera Lung Infections at an Adult Cystic Fibrosis Program.

Rationale: Outbreaks of nontuberculous mycobacteria (NTM) among people with cystic fibrosis (pwCF) have been reported at CF centers with conflicting conclusions. The occurrence of NTM at the UVMC (University of Vermont Medical Center) adult CF program was investigated. Objectives: Use the HALT NTM (Healthcare-associated Links in Transmission of NTM) toolkit to investigate the healthcare-associated transmission and/or acquisition of NTM among pwCF having genetically similar NTM isolates. Methods: Whole genome sequencing of NTM isolates from 23 pwCF was conducted to identify genetically similar NTM isolate clusters (30 or fewer single-nucleotide polymorphism differences). The epidemiological investigation, comparison of respiratory and healthcare environmental isolates, and home residence watershed mapping were analyzed. Results: Whole genome sequencing analysis revealed two clusters of NTM isolates (Mycobacterium avium and M. intracellulare ssp. chimaera) among pwCF. The epidemiologic investigation demonstrated opportunities for healthcare-associated transmission within both clusters. Healthcare environmental M. avium isolates revealed no genetic similarity to respiratory isolates. However, M. intracellulare ssp. chimaera respiratory isolates revealed greater genetic similarity to a hospital water biofilm isolate than to each other. Neither cluster had all subjects residing in the same watershed. Conclusions: This study suggests the healthcare-associated transmission of M. avium among pwCF is unlikely at UVMC but supports the healthcare-associated environmental acquisition of M. intracellulare ssp. chimaera. The presence of genetically similar isolates alone is insufficient to confirm healthcare-associated transmission and/or acquisition. The HALT NTM toolkit standardizes outbreak investigation with genetic analysis, epidemiologic investigation, healthcare environmental sampling, and home of residence watershed identification to test the frequency and nature of healthcare-associated NTM transmission among pwCF.

Vermamoeba vermiformis resides in water-based heater-cooler units and can enhance Mycobacterium chimaera survival after chlorine exposure.

BACKGROUND: Mycobacterium chimaera colonizes water-based heater-cooler units (HCUs), from which it can spread to patients during surgery. Vermamoeba vermiformis is a free-living waterborne amoeba, which was consistently present within HCUs. AIM: To determine whether these amoebae can be involved in the persistent presence of M. chimaera. METHODS: An in-vitro disinfection model. FINDINGS: Increased survival of M. chimaera was observed after chlorine exposure in the presence of V. vermiformis. Confocal microscopy demonstrated the intracellular presence of M. chimaera in V. vermiformis. CONCLUSION: In this way, V. vermiformis can contribute to the persistent presence of M. chimaera in HCUs. Cleaning and disinfection protocols should take this phenomenon into account.

Longitudinal increase in the detection rate of Mycobacterium chimaera in heater-cooler device-derived water samples.

BACKGROUND: Colonization with Mycobacterium chimaera and other non-tuberculous mycobacteria (NTM) has been reported for heater-cooler devices (HCDs) produced by several manufacturers. Up until now, exclusively LivaNova (London, UK) HCDs have been associated with M. chimaera infections after cardiac surgery. The vast majority of studies on HCD colonization were cross-sectional. AIM: We were interested in longitudinal dynamics of mycobacterial growth in HCD water samples and analysed data of a prospective mycobacterial surveillance of five LivaNova 3T HCDs. METHODS: Five LivaNova HCDs were subjected to prospective mycobacterial surveillance. For each HCD and the total of HCDs, results of mycobacterial detection were analyzed. Logistic regression was applied to model the association between growth of any NTM or M. chimaera and duration of HCD use. RESULTS: Non-tuberculous mycobacteria were isolated in 319 (48.0%, 21 water samples grew more than one mycobacterial species) of a total of 665 water samples. The most frequently detected species were M. chimaera (N = 247/319, 77.4%), Mycobacterium gordonae (46/319, 14.4%) and Mycobacterium paragordonae (34/319, 10.7%). Detection rates increased prospectively for any NTM (odds ratio (OR) per year in use: 1.60, 95% confidence interval (CI) 1.17-2.24, P<0.001) and for M. chimaera (OR per year in use: 1.67, 95% CI 1.11-2.57, P<0.01). CONCLUSION: Longer duration of HCD use was associated with higher detection rates for any NTM and M. chimaera, respectively.

A solution for global hygienic challenges regarding the application of heater-cooler systems in cardiac surgery.

71.759 surgical procedures were performed in 2019 with the aid of cardiopulmonary bypass in Germany. To adjust the patient's body temperature on extracorporeal circulation, the application of a heater-cooler unit (HCU) is mandatory. However, in case of insufficient sanitisation of HCU, life-threatening infections can be transmitted by the device to the patients, including Legionella bacteria, Mycobacterium chimaera, Pseudomonas aeruginosa. To avoid disease transmission, as a requirement for safe medical practice established by regulatory authorities, HCUs must be regularly disinfected by hazardous chemicals posing a danger for both handling humans and the environment. Therefore, to comply with regulations, HCU manufacturers have introduced both timely and financially extensive sanitisation procedures. Our paper describes a novel, effective and easy to handle disinfection method for the above problematics without utilising hazardous chemicals. The method's technical principle is electrolysis, resulting in drinking water quality regarding the analysed germs in the worldwide most commonly utilised heater-cooler device. The main aim of the study was to prove the efficacy and reliability of the device cleansing process. Furthermore, the economic impact of the novel method was evaluated. Therefore, we have undertaken 60 microbiological sampling series between December 2019 and November 2020 from a conventional HCU (3T LivaNova, Germany). During the total investigational period, no contamination with Pseudomonas aeruginosa or Legionellae could have been demonstrated in the HCU. The extreme slow-growing nontuberculous M. chimaera was detected only in one sample obtained from diamond electrode cleansed HCU water, and source of contamination was promptly eliminated by a simple technical modification of the device test-site. Additionally, the diamond electrode application is beneficial for eliminating potentially hazardous cleansing material from the process, which may affect otherwise both patients operated on cardiopulmonary bypass and the perfusionists.

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.

Disseminated Mycobacterium chimaera infection favoring the development of Kaposi's sarcoma: a case report.

BACKGROUND: Disseminated Mycobacterium chimaera infection is an emerging disease in people undergone to cardiothoracic surgery, which need to be suspected also with atypical presentations. CASE PRESENTATION: We report the case of a 74-year-old man with fever of unknown origin, purple nodules on both feet and a history of open-heart surgery. Imaging investigations showed an abscess near aortic bioprosthesis but screening for endocarditis resulted negative and pyrexia did not respond to antibiotic therapy. A biopsy of cutaneous lesions showed HHV8-related Kaposi's sarcoma, so bone marrow biopsy was executed with evidence of HHV8 localization. Bone marrow and urine mycobacterial cultures resulted positive for M. chimaera and a specific antimicrobial therapy was started, with apyrexia after 7 weeks. CONCLUSIONS: M. chimaera infection should be always investigated as a possible etiology of fever of unknow origin in people with a history of open-heart surgical intervention, even with negative mycobacterial blood cultures. The possible role of disseminated infection in inducing immunodepression with the occurrence of other opportunistic diseases (such as Kaposi's sarcoma) cannot be excluded.

Mycobacterium chimaera lung infection and empyema in a patient without cardiopulmonary bypass.

Mycobacterium chimaera is a nontuberculous mycobacterium that belongs to the Mycobacterium avium complex. Invasive infections are very rare and have been associated with contaminated heater-cooler water systems used during cardiopulmonary bypass. There is usually a long latency period and patients have nonspecific symptoms that can result in a delayed diagnosis or misdiagnosis. We report a case of M. chimaera infection in a man who presented with worsening shortness of breath and was found to have pleural effusion. The patient did not have any history of cardiopulmonary bypass surgery, which raises concerns about community spread of this rare infection and needs further investigation in the general population. Furthermore, he had a history of sarcoidosis and was on immunosuppressive medications, which might suggest that immunosuppressed patients can acquire this infection without the described risk factors.

Investigating the Origin of Mycobacterium chimaera Contamination in Heater-Cooler Units: Integrated Analysis with Fourier Transform Infrared Spectroscopy and Whole-Genome Sequencing.

Mycobacterium chimaera is ubiquitously spread in the environment, including factory and hospital water systems. Invasive cases of M. chimaera infection have been associated with aerosols produced by the use of heater-cooler units (HCU) during cardiac surgery. The aim of this study was to evaluate for the first time the performance of IR-Biotyper system on a large number of M. chimaera isolates collected from longitudinal environmental HCUs samples and water sources from hospitals located in three Italian provinces. In addition, IR-Biotyper results were compared with whole-genome sequencing (WGS) analysis, the reference method for molecular epidemiology, to investigate the origin of M. chimaera contamination of HCUs. From November 2018 to May 2021, 417 water samples from 52 HCUs (Stockert 3T, n = 41 and HCU40, n = 11) and 23 hospital taps (used to fill the HCU tanks) were concentrated, decontaminated, and cultured for M. chimaera. Positive cultures (n = 53) were purified by agar plate subcultures and analyzed by IR-Biotyper platform and Ion Torrent sequencing system. IR-Biotyper spectra results were analyzed using a statistical approach of dimensionality reduction by linear discriminant analysis (LDA), generating three separate clusters of M. chimaera, ascribable to each hospital. Furthermore, the only M. chimaera-positive sample from tap water clustered with the isolates from the HCUs of the same hospital, confirming that the plumbing system could represent the source of HCU contamination and, potentially, of patient infection. According to the genome-based phylogenies and following the classification proposed by van Ingen and collaborators in 2017, three distinct M. chimaera groups appear to have contaminated the HCU water systems: subgroups 1.1, 2.1, and branch 2. Most of the strains isolated from HCUs at the same hospital share a highly similar genetic profile. The nonrandom distribution obtained with WGS and IR-Biotyper leads to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, in addition with the current hypothesis that contamination occurs at the HCU production site. This opens the possibility that other medical equipment, such as endoscope reprocessing device or hemodialysis systems, could be contaminated by M. chimaera. IMPORTANCE Our manuscript focuses on interventions to reduce waterborne disease transmission, improve sanitation, and control infection. Sanitary water can be contaminated by nontuberculous Mycobacteria, including M. chimaera, a causative agent of invasive infections in immunocompromised patients. We found highly similar genetic and phenotypic profiles of M. chimaera isolated from heater-cooler units (HCU) used during surgery to thermo-regulate patients' body temperature, and from the same hospital tap water. These results lead to the hypothesis that M. chimaera subtypes circulating in the local plumbing colonize HCUs through the absolute filter, adding to the current hypothesis that contamination occurs at the HCU production site. In addition, this opens the possibility that other medical equipment using sanitized water, such as endoscope reprocessing devices or hemodialysis systems, could be contaminated by nontuberculous Mycobacteria, suggesting the need for environmental surveillance and associated control measures.

A Case of Cavitary Mycobacterium chimaera.

Mycobacterium chimaera is a nontuberculous mycobacterium typically associated with heater-cooler units used in cardiac bypass procedures and is usually of low virulence. Here we present a patient with advanced Mycobacterium chimaera infection without typical risk factors.