Vancomycin Resistant Enterococci Infection

The goal of this clinical trial is to determine if oral vancomycin can prevent C.diff infection in adults who are critically ill and are at high risk of C.diff infection due to their medical conditions and being in the hospital. It will also help us learn about the safety of the drug in this setting. The main questions the trial aims to answer are: * Does oral vancomycin lower the rate of C.diff infection in high-risk patients? * Does C.diff carrier status change the C.diff infection rate as well as clearance of carrier status when vancomycin is used as primary prophylaxis? Researchers will compare the oral, active drug vancomycin to a placebo (a look-alike substance that contains no drug) to determine if vancomycin works to prevent C.diff infection in the hospital. Participants will: * Take oral vancomycin or a placebo while they receive systemic antibiotic(s) for up to five days after the last dose of said systemic antibiotic(s). The treatment of said systemic antibiotic(s) is not to exceed 21 days. * When discharged from the hospital, participants will continue to take the study medication in the event he/she did not complete the intended course of the study medication while in the hospital. * Participants will provide stool sample or rectal swabs for to assess their C.diff carrier status as well as any change in stool microbiome status, including VRE (vancomycin resistant Enterococcus) * After completion of the intervention period, participants will be contacted via telephone to assess if they developed diarrhea or any untoward effects of study medication.

The gut microbiota is critical to health and functions with a level of complexity comparable to that of an organ system. Dysbiosis, or alterations of this gut microbiota ecology, have been implicated in a number of disease states. Fecal microbiota transplantation (FMT), defined as infusion of feces from healthy donors to affected subjects, is a method to restore a balanced gut microbiota and has attracted great interest in recent years due to its efficacy and ease of use. FMT is now recommended as the most effective therapy for CDI not responding to standard therapies. Recent studies have suggested that dysbiosis is associated with a variety of disorders, and that FMT could be a useful treatment. Randomized controlled trial has been conducted in a number of disorders and shown positive results, including alcoholic hepatitis, Crohn's disease (CD), ulcerative colitis (UC), pouchitis, irritable bowel syndrome (IBS), hepatic encephalopathy and metabolic syndrome. Case series/reports and pilot studies has shown positive results in other disorders including Celiac disease, functional dyspepsia, constipation, metabolic syndrome such as diabetes mellitus, multidrug-resistant, hepatic encephalopathy, multiple sclerosis, pseudo-obstruction, carbapenem-resistant Enterobacteriaceae (CRE) or Vancomycin-resistant Enterococci (VRE) infection, radiation-induced toxicity, multiple organ dysfunction, dysbiotic bowel syndrome, MRSA enteritis, Pseudomembranous enteritis, idiopathic thrombocytopenic purpura (ITP), and atopy. Despite FMT appears to be relatively safe and efficacious in treating a wide range of disease, its safety and efficacy in a usual clinical setting is unknown. More data is required to confirm safety and efficacy of FMT. Therefore, the investigators aim to conduct a pilot study to investigate the efficacy and safety of FMT in a variety of dysbiosis-associated disorder.

The goal of this observational study is to investigate how bacterial populations from the intestine and mouth of patients change during the hospitalization period and evaluate if some populations of specific bacteria increase or decrease the risk of acquiring an infection or becoming colonized by pathogenic bacteria. Participants will have the following samples collected during enrollment: stool samples (maximum 2x/week), blood draws (1x/week), oral swab (1x/week).