![]() ![]() chimaera infection and who had testing of cell-free plasma by NGS (plasma NGS) between February 2017 and April 2018. chimaera exposure risk who developed invasive M. This was a retrospective study of patients with a history of cardiac surgery performed at a Southern California hospital with known M. In this report, we describe the application of a plasma-based NGS test for the diagnosis of invasive M. ![]() This approach takes advantage of the cell-free DNA (cfDNA) present in plasma that can be derived from potentially any source within the body, including pathogens at deep sites of infection. The application of NGS to a blood sample is one way to overcome this hurdle and has been used successfully in other areas of medicine for noninvasive diagnosis. Advances in next-generation sequencing (NGS) and bioinformatics have been utilized for the direct detection of pathogen nucleic acid and hold great promise, but invasive procedures are generally necessary to obtain appropriate clinical specimens for testing. Given these challenges, there is an urgent need for innovative diagnostic approaches. chimaera are typically available only at reference or research laboratories, further delaying confirmation of the causative pathogen. While some clinical laboratories can identify MAC isolates from AFB culture, the specialized molecular methodologies required for differentiation of M. Standard confirmatory testing utilizing acid-fast bacilli (AFB) culture often requires invasive sampling, has limited sensitivity, and can take up to 8 weeks for mycobacterial growth. Clinical symptoms, including fatigue, fever, sweats, cough, dyspnea and weight loss, are non-specific and indolent, manifesting as long as 6 years after surgery. There are several challenges inherent in the diagnosis of M. Reported mortality has been as high as 50%. While infection can be localized to the sternal wound, disseminated disease involving the liver, spleen, bone marrow, kidney, bones, joints or eyes has been typical among cardiac surgery patients with implanted prosthetic material. The potential for widespread exposure to infection is significant in the US alone, LivaNova 3 T HCDs have been in use since 2006, comprise over 60% of the HCD market, and are utilized for over 250,000 cardiac surgeries each year. chimaera isolates from infected patients and HCD water samples worldwide has demonstrated sequence similarity, suggesting point source contamination at the time of device manufacturing. During HCD operation, the organism has been demonstrated to aerosolize via the exhaust of contaminated devices, resulting in airborne inoculation of the surgical site. chimaera contamination of the LivaNova 3 T (LivaNova, London, UK) heater-cooler device (HCD) used for thermoregulation during cardiothoracic surgery has been linked to an ongoing global outbreak of serious infections, including in Europe, North America, Australia and New Zealand. Mycobacterium chimaera, a nontuberculous mycobacterium belonging to the Mycobacterium avium complex (MAC), is an opportunistic human pathogen that is ubiquitous in the environment, particularly in water sources. chimaera noninvasively and significantly faster than AFB culture, making it a promising new diagnostic tool. Invasive procedures were performed in 90% of cases, and in 5 patients (50%), mycobacterial growth was achieved only by culture of these deep sites. ![]() Of 24 AFB blood cultures obtained in this cohort, only 4 (17%) were positive. In contrast, AFB cultures required a median of 20 days to turn positive, and the median time for confirmation of M. ![]() In 7 of these 9 cases (78%), plasma NGS was the first test to provide microbiologic confirmation of M. chimaera in 9 of 10 patients (90%) with invasive disease in a median of 4 days from specimen collection, including all 8 patients with disseminated infection. chimaera infection and underwent testing by plasma NGS between February 2017 and April 2018. We conducted a retrospective study of 10 patients with a history of cardiac surgery who developed invasive M. We describe the performance of a plasma-based next-generation sequencing test (plasma NGS) for the diagnosis of M. Standard diagnostic methods using acid-fast bacilli (AFB) culture often require invasive sampling, have low sensitivity, and can take weeks to result. chimaera infection is hampered by its long latency and non-specific symptoms. There is an ongoing outbreak of Mycobacterium chimaera infections among patients exposed to contaminated heater-cooler devices used during cardiac surgery. ![]()
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