756. Low Lactobacillus spp. Abundance Characterizes the Fecal Microbiome of Patients Acquiring Multidrug-Resistant Organisms During Hospitalization
Session: Poster Abstract Session: All Things Microbiome
Friday, October 9, 2015
Room: Poster Hall
  • Poster_IDWeek_2015_Final_PDF.pdf (1.6 MB)
  • Background: The emergence and dissemination of Multidrug-Resistant Organisms (MDRO) is a global threat. New strategies to limit their spread are needed. Hospitalized patients are frequently exposed to antimicrobials and constitute an important source of MDRO. We aimed to analyze the fecal microbiota of hospitalized patients to explore whether unique microbial signatures are associated with increased risk of MDRO acquisition during hospitalization.

    Methods: The study population consisted of adults recently (<48h) hospitalized acutely on medical floors who were receiving antimicrobials at enrollment. Two perianal/rectal swabs were obtained at enrollment (baseline) and at discharge (follow-up). Specimens were processed for MDRO detection (conventional cultures), and microbial community assessment (16S rRNA sequencing, Illumina MiSeq platform).  Acquisition (MDRO+) was defined as MDRO detected on follow-up but not on baseline swab. Patients colonized with MDRO at baseline were excluded from the analysis. Within-sample biodiversity (alpha diversity), between-sample biodiversity (beta diversity), and differentially abundant features were compared between patients who acquired or did not acquire MDRO during hospitalization.

    Results: Of 25 patients included in the analysis, 7 (28%) acquired at least one MDRO (MDRO+), and 18 did not (MDRO-); demographic and clinical characteristics were similar between groups. Analysis showed no differentially abundant features at the phylum level between MDRO+ and MDRO-. Overall, the most abundant phyla were Firmicutes (45%), Bacteroidetes (37%), Actinobacteria (7.8%), and Proteobacteria (1.3%). At the genus level, MDRO+ patients had a statistically significant, and biologically consistent lower Lactobacillus spp. abundance compared to the MDRO-group (LDA score = 3.97; P = 0.04) (Figure 1). Alpha diversity metrics were similar between groups, and the analysis of beta diversity did not find any specific clustering pattern.

    Conclusion: Since low Lactobacillus spp. abundance characterized the microbiota of patients who acquired MDRO, these commensal species may have a protective role against MDRO acquisition.

    Figure 1: Relative Lactobacillus spp. abundance at baseline

    Rafael Araos Bralic, MD MMSc, Infectious Diseases, Clinica Alemana de Santiago - Universidad del Desarrollo, Santiago, Chile, Albert K. Tai, PhD, Tufts University Core Facility (TUCF) Genomics Core, Boston, MA, Graham M Snyder, MD, SM, Department of Medicine, Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, MA, Martin Blaser, MD, FIDSA, New York University Langone Medical Center, New York, NY and Erika D'agata, MD, MPH, Rhode Island Hospital, Brown University, Providence, RI


    R. Araos Bralic, None

    A. K. Tai, None

    G. M. Snyder, None

    M. Blaser, None

    E. D'agata, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.