The high prevalence of among nursing home elders associates with a dysbiotic microbiome.

disproportionally affects the elderly living in nursing homes (NHs). Our objective was to explore the prevalence of in NH elders, over time and to determine whether the microbiome or other clinical factors are associated with colonization.We collected serial stool samples from NH residents. prevalence was determined by quantitative polymerase-chain reaction detection of Toxin genes and ; microbiome composition was determined by shotgun metagenomic sequencing. We used mixed-effect random forest modeling machine to determine bacterial taxa whose abundance is associated with prevalence while controlling for clinical covariates including demographics, medications, and past medical history.We enrolled 167 NH elders who contributed 506 stool samples. Of the 123 elders providing multiple samples, 30 (24.4%) elders yielded multiple samples in which was detected and 78 (46.7%) had at least one positive sample. Elders with positive samples were characterized by increased abundances of pathogenic or inflammatory-associated bacterial taxa and by lower abundances of taxa with anti-inflammatory or symbiotic properties. Proton pump inhibitor (PPI) use is associated with lower prevalence of (Odds Ratio 0.46; 95%CI, 0.22-0.99) and the abundance of bacterial species with known beneficial effects was higher in PPI users and markedly lower in elders with high prevalence. is prevalent among NH elders and a dysbiotic gut microbiome associates with colonization status. Manipulating the gut microbiome may prove to be a key strategy in the reduction of in the NH.