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In this work, we report 2 cases of vancomycin-resistant Enterococcus faecium bacteremia with development of daptomycin resistance in 2 patients with acute myeloid leukemia and myelodysplastic syndrome. Mutations related to daptomycin-nonsusceptible phenotype in liaSR genes were found in all strains of the study, including those with a minimum inhibitory concentration <1 µg/mL collected before daptomycin therapy. Epidemiological investigation using core genome single nucleotide polymorphism and core genome multilocus sequence typing revealed clonality of all the isolates. In this study, we conclude that real-time genome sequencing of clinical isolates can provide rapid access to timely information on daptomycin-resistant genotypes that would help clinicians speed up and optimize the selection of the antibiotic for treatment.

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Multiple myeloma (MM) patients frequently attain a bone marrow (BM) minimal residual disease (MRD) negativity status in response to treatment. We identified 568 patients who achieved BM MRD negativity following autologous stem cell transplantation (ASCT) and maintenance combination therapy with an immunomodulatory agent and a proteasome inhibitor. BM MRD was evaluated by next generation flow cytometry (sensitivity of 10-5 cells) at 3 to 6 months intervals. With a median follow up of 9.9 years from diagnosis (range, 0.4 - 30.9), 61% of patients maintained MRD negativity, while 39% experienced MRD conversion at a median of 6.3 years (range, 1.4 - 25). The highest risk of MRD conversion occurred within the first 5 years after treatment and was observed more often in patients with abnormal metaphase cytogenetic abnormalities (95%vs. 84%; P = 0.001). MRD conversion was associated with a high risk of relapse and preceded it by a median of 1.0 year (range, 0 - 4.9). However, 27% of MRD conversion positive patients had not yet experienced a clinical relapse with a median follow-up of 9.3 years (range, 2.2 - 21.2). Landmark analyses using time from ASCT revealed patients with MRD conversion during the first 3 years had an inferior overall and progression-free survival compared to patients with sustained MRD negativity. MRD conversion correctly predicted relapse in 70%, demonstrating the utility of serial BM MRD assessment to complement standard laboratory and imaging to make informed salvage therapy decisions.

Here, we present complete genome sequences of four Enterococcus faecium isolates, obtained from two patients with apparent vancomycin-resistant Enterococcus faecium bacteremia; these isolates also carried two mutations known to be associated with daptomycin resistance. Sequences were obtained using de novo and hybrid assembly of Oxford Nanopore and Illumina sequence data.