The human intestines harbor an abundant, diverse bacterial community that has critical influences on the host. The microbiota of most healthy individuals is comprised of up to 1% of Enterobacteriaceae, a family of bacteria that contains many common pathogens such as Escherichia coli and Salmonella. However, the intestinal microbiota of some individuals has a greater abundance of Enterobacteriaceae, but the reasons for this dichotomy remain unclear. It is possible that some individuals harbor bacterial species or strains that fill the same niche as Enterobacteriaceae species, thereby limiting colonization and/or growth in the gut by Enterobacteriaceae. Because Enterobacteriaceae species are often implicated in disease, it is important to understand why they persist at high levels in the intestinal microbiota of some but not others. Identifying microbes that may provide colonization resistance to Enterobacteriaceae species will inform the development of microbiome-based therapeutics. Using metagenomic data of intestinal microbial communities from various patient cohorts, a species co-occurrence network was built to determine if the presence or absence of certain species correlates with the presence/absence of Enterobacteriaceae species. Preliminary findings reveal that the presence of Bacteroides and Prevotella species in a microbial community negatively correlates with presence of Enterobacteriaceae species.