Mycobacterium infection from a cardiopulmonary bypass heater-cooler unit in a patient with steroid-induced immunosuppression

Mycobacterium chimaera chorioretinitis preceding central nervous system lesions: a case report and review of the literature

Background

Mycobacterium chimaera ocular infection is a rare disease that is linked to bypass devices used during cardiothoracic surgeries. Reported cases in the literature of ocular involvement preceding CNS involvement are based on clinical exam with no neuroimaging. Here we present a case of M. chimaera ocular infection with no CNS M. chimaera lesions on brain magnetic resonance imaging (MRI).

Case presentation

A 59-year-old female presented with altered mental status and blurred vision in February 2021. Her past medical history was significant for aortic valve replacement and ascending aortic aneurysm repair in 2017 complicated by known M. chimaera infection. She had been receiving azithromycin, ethambutol, rifampin, and amikacin as systemic anti-mycobacterium treatment. Her dilated fundus exam showed numerous yellow placoid circular lesions scattered throughout the macula and peripheral retina in both eyes with associated vitritis. Systemic workup, including brain MRI showed no acute infectious lesions. Her infections workup was unremarkable except for a positive toxoplasma IgM, for which she was treated with sulfamethoxazole/trimethoprim. One month later, a head computed tomography showed new numerous scattered round foci of hyperdensity throughout the cerebrum and brainstem thought to be foci of M. chimaera infection. Clofazimine was added per culture and sensitivity. MRI brain 1 month later showed mild decrease in conspicuity and number of these intensities while on anti-mycobacterium treatment. Her cognition had improved at that time as well. She was seen in retina clinic 2 months later where her exam showed similar retinal lesions with no associated vitritis or anterior chamber cell in bilateral eyes, suggesting a lack of active infection. Optical coherence tomography macula showed parafoveal cystoid macular edema bilaterally. She was started on steroidal and non-steroidal anti-inflammatory eye drops.

Conclusions

To the best of our knowledge, this is the first case in the literature to report M. chimaera chorioretinitis with concomitant negative neuroimaging. Chorioretinal M. chimaera lesions should motivate high suspicion of CNS involvement prompting early neurological work up.

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.

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.

Mycobacterium chimaera Hepatitis: A New Disease Entity

Mycobacterium chimaera was identified as a species within the Mycobacterium avium complex in 2004. Until recently, it was predominantly seen in immunocompromised patients. In 2015, an outbreak of disseminated M. chimaera disease was described in European patients after undergoing open-heart surgery in which contaminated heater-cooler water units were used. Using whole genomic sequencing and phylogenetic analysis, investigators found a highly clonal outbreak from the German manufacturing site of the heater-cooler water units. This outbreak has now proven to be world-wide. Patients present with fever, fatigue, and weight loss months to many years after surgery. They are found to have systemic manifestations, including endocarditis, pancytopenia, renal dysfunction, chorioretinitis, and hepatitis. Preliminary reports suggest a high mortality rate despite aggressive treatment. In some patients, the predominant laboratory abnormalities are elevations in liver function tests, leading to diagnostic hepatobiliary work-ups, including liver biopsy. The pathologic changes in the liver have not yet been described. Herein, we report the clinicopathologic findings of the largest series of M. chimaera liver disease in the United States to date: 7 cases within a large, multihospital health care network. Five (71%) patients died of disease, despite aggressive treatment. Liver function test abnormalities were predominantly biliary: mean values of alkaline phosphate 288 U/L, aspartate aminotransferase 79 U/L, alanine aminotransferase 64 U/L. All 7 biopsies showed a consistent and characteristic dual pattern of injury: small, ill-formed collections of sinusoidal histiocytes with rare multinucleated giant cells, and scattered architectural changes of venous outflow obstruction. Two (29%) cases showed mild pericellular fibrosis. Nodular regenerative hyperplasia was seen in 2 (29%) cases, consistent with a sinusoidal/venous obstructive pattern of injury. We postulate that the sinusoidal location of the granulomas contributes to the venous obstructive changes. Recognition of this characteristic dual pattern of injury can allow pathologists to suggest the diagnosis and prompt the appropriate diagnostic and therapeutic interventions.

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.

Responding to Mycobacterium chimaera heater-cooler unit contamination: international and national intersectoral collaboration coordinated in the state of Queensland, Australia

BACKGROUND

The index case of Mycobacterium chimaera infection in a patient following open cardiac surgery in the state of Queensland, Australia prompted a centralized coordinated response to mitigate the risk.

AIM

To describe the public health response to M. chimaera contamination of heater-cooler units (HCUs) and patient infection.

METHODS

A public health sector strategy was developed with national and international consultation to respond to the threat of HCUs contaminated with M. chimaera. Data linkage of non-tuberculous mycobacterium notifications and selected procedures was undertaken where potential use of HCUs was identified through hospitalization records. Water sampling and testing protocols were standardized. Public disclosure and patient notification were undertaken.

FINDINGS

A single case of disseminated M. chimaera infection in a patient has been diagnosed to date in Queensland, Australia. Ten of 12 (83%) LivaNova Stockert 3T HCUs from five hospitals tested positive for M. chimaera. In total, 5650 patients were notified by post of their potential risk of exposure. Use of the telehealth call centre was modest. M. chimaera was also found in extracorporeal membrane oxygenation heater units produced by two other device manufacturers, four of which tested positive prior to commissioning for use.

CONCLUSIONS

Rapid international collaboration optimized the Queensland Health response to potential M. chimaera exposure during cardiac surgery. State-wide collaboration ensured a transparent, consistent approach to contacting patients and informing the public of the potential risk. A framework for ongoing risk management, clinical awareness and laboratory diagnosis was established. No further cases of M. chimaera infection have been identified in Queensland.

Mycobacterium chimaera Infections Associated With Contaminated Heater-Cooler Devices for Cardiac Surgery: Outbreak Management

The global outbreak of Mycobacterium chimaera infections associated with heater-cooler devices (HCDs) presents several important, unique challenges for the infection prevention community. The primary focus of this article is to assist hospitals in establishing a rapid response for identification, notification, and evaluation of exposed patients, and management of HCDs with regard to placement and containment, environmental culturing, and disinfection.

Microbiological problems and biofilms associated with Mycobacterium chimaera in heater-cooler units used for cardiopulmonary bypass

The role of heater-cooler units (HCUs) in the transmission of Mycobacterium chimaera during open heart surgery has been recognized since 2013. Subsequent investigations uncovered a remarkable global outbreak reflecting the wide distribution of implicated devices. HCUs are an essential component of cardiopulmonary bypass operations and their withdrawal would severely affect capacity for life-saving cardiac surgery. However, studies have demonstrated that many HCUs are contaminated with a wide range of micro-organisms, including M. chimaera and complex biofilms. Whole genome sequencing of M. chimaera isolates recovered from one manufacturer's HCUs, worldwide, has demonstrated a high level of genetic similarity, for which the most plausible hypothesis is a point source contamination of the devices. Dissemination of bioaerosols through breaches in the HCU water tanks is the most likely route of transmission and airborne bacteria have been shown to have reached the surgical field even with the use of ultraclean theatre ventilation. Controlling the microbiological quality of the water circulating in HCUs and reducing biofilm formation has been a major challenge for many hospitals. However, enhanced decontamination strategies have been recommended by manufacturers, and, although they are not always effective in eradicating M. chimaera from HCUs, UK hospitals have not reported any new cases of M. chimaera infection since implementing these mitigation strategies. Water safety groups in hospitals should be aware that water in medical devices such as HCUs may act as a vector in the transmission of potentially fatal water-borne infections.