Microbiome and resistome characterization of patients colonized with carbapenem-resistant Enterobacterales by long-read metagenomic next-generation sequencing of rectal swabs.

Objectives: Evaluation of differences in the intestinal microbiome and resistome among high-risk patients (i.e. intensive care, oncology, transplant recipients) who are and are not colonized with carbapenem-resistant Enterobacterales (CRE). Methods: One hundred and twelve rectal swabs were obtained from 85 patients with known CRE colonization status and cohorted. Long-read metagenomic next-generation sequencing (mNGS) was performed on rectal swabs. Microbiome and resistome analysis were performed by assessing α-diversity, β-diversity, relative abundance assessment and linear discriminant analysis effect size (LEfSe), comparing patients colonized (CRE positive) and not colonized (CRE negative) with CRE. Longitudinal analysis of sequential swabs collected over multiple hospital encounters on a subset of patients was performed at the patient level. Results: The microbiomes of cohorts were similar when comparing α- and β-diversity measures and relative abundance. LEfSe analysis identified Gram-negative pathobionts enriched among CRE-positive samples and Gram-positive taxa enriched among CRE-negative samples. α-Diversity of the resistome differed at class, gene and allele levels. Relative abundance and LEfSe analysis demonstrated enrichment of genes conferring β-lactam resistance among CRE-positive patients; LEfSe also demonstrated enrichment of antimicrobial resistance genes to multiple antimicrobial classes. At the patient level, fluctuations in the microbiome and resistome among longitudinally collected swabs were associated with antibiotic exposure. Conclusions: Differences between the microbiomes of CRE-positive- and CRE-negative-colonized patients at the cohort level were relatively muted, whereas statistically significant differences were observed among their resistomes. In patients followed longitudinally, shifts in microbiome and resistome composition were dramatic in between encounters and antibiotic exposures.