2846. Perirectal Samples for Analysis of the Gut Microbiota as a Predictive Tool for Multi-drug-Resistant Organism (MDRO) Acquisition in Nursing Facility (NF) Patients

BACKGROUND: Most research examining the association between gut microbiota disruption and MDRO acquisition has been done in acute care settings. Obtaining stool samples in older NF adults is challenging. We hypothesized that perirectal samples can be used as a proxy of the gut microbiota. This prospective cohort study investigated the association between perirectal swab-derived gut microbiota features in newly admitted NF patients and the acquisition of vancomycin-resistant Enterococcus and/or resistant Gram-negative bacteria (rGNB) within 14 days. METHODS: Patients were recruited at 6 MI NFs from September 2016 to October 2018 as part of a larger NIH-funded trial. Colonization status was determined by culture swabs collected from multiple body sites at enrollment, d7, and d14. Our analysis focused on patients with no MDRO at baseline, a perirectal swab collected at baseline, and at least one follow-up visit. The V4 region of the 16S rRNA gene was sequenced from samples and processed with the mothur bioinformatics pipeline. Sequences typically associated with the skin microbiota were removed. The primary outcome was any MDRO acquisition. Exposures of interest included patient and microbiota characteristics. The Microbiome Health Index (MHI) was used to assess microbiota health. An MHI of 0 indicates a balanced abundance between taxa associated with protection and dysbiosis; an MHI above/below 0 suggests better/poorer health, respectively (Figure 1). RESULTS: Among 60 eligible patients (Table 1), 18 (30%) acquired MDROs within 14 days of enrollment (3 VRE, 13 rGNB, 2 both). The baseline microbiota features differed significantly in those who acquired a new MDRO. Of the major 8 phyla found across samples, patients who acquired an MDRO were depleted in the number of phyla present (4.4 ± 1.1 vs. 5 ± 1.1; P = 0.08) (Figure 2). The log-transformed relative abundance of Enterococcus was enriched in patients who acquired an MDRO (−0.7 ± 3.41) compared with those who did not (−4.2 ± 4.8; P < 0.01) (Figure 3). An MHI below 0 was predictive of MDRO acquisition after adjusting for catheter use within 30 days before baseline (adjusted OR 4.9; 95% CI 1.1–21.1). CONCLUSION: Microbiota metrics calculated from perirectal samples are predictive of MDRO acquisition. The clinical utility of perirectal samples warrants further assessment. [Image: see text] [Image: see text] [Image: see text] [Image: see text] DISCLOSURES: All Authors: No reported Disclosures.