Plasma mcfDNA molecules can be mapped to taxa found in matched stool samples. (A) Quantified MPM of taxa that were identified using both plasma mcfDNA sequencing and 16s rRNA sequencing of matching stool samples (n = 18 unique patients). Each point is a blood sample; the vertical axis plots the aggregated MPM in plasma, at the genus level, that were also observed in the paired fecal sample. (B) A single patient time course, in a recipient of a reduced-intensity (fludarabine/melphalan) allograft, who developed acute GVHD on day 21. In addition to the chemotherapy and antibiotic therapy shown in the top panel, the patient received acyclovir as antiviral prophylaxis and micafungin (until day 7), followed by voriconazole, consistent with institutional antifungal prophylaxis practice. Red squares represent blood sampling points. IV, intravenous; PO, per os.