Project Summary- CORE 1 Clostridioides difficile infection (CDI) is the leading cause of antibiotic-associated diarrhea in the United States and associated with significant morbidity and mortality. Patients with CDI have high rates of recurrence of disease, with 20-30% of adults and children having additional infections. Evaluation of the immune response to CDI has focused primarily on the antibody response to CDI toxins. Unfortunately, CDI therapeutics and toxoid vaccines focused primarily on the immune response to toxins have produced disappointing results in CDI prevention to date. Additional evaluation of the host immune response to CDI is critical and best evaluated through basic and translational research as outlined in the Vanderbilt Antibody and Antigen Discovery for Clostridioides difficile Vaccines (VANDy-CdV) project. The Clinical Data and Biospecimen Repository Core (Core 1) will support the goals of the VANDy-CdV through a rich source of patient biospecimens and linked clinical data. Core 1 will be responsible for all elements of patient recruitment, enrollment, biospecimen collection, database integration, and patient retention. Trained research personnel will identify patients with CDI at a large tertiary care medical center through clinical microbiology laboratory records which process over 450 samples for C. difficile testing per month. After consent, residual stool samples will be obtained. At two weeks and two months after CDI, serum, whole blood, and saliva will be obtained. Clinical data and CDI-related outcomes will be measured at two weeks, two months, and six months after initial infection. Core 1 will enroll 40 CDI case patients identified through laboratory records and an additional 40 healthy controls recruited through primary care clinics. Core 1 will process, aliquot, and log all biospecimens for future use to support the aims of the VANDy-CdV team. Core 1 will also establish and maintain a repository of clinical data elements pre-determined to be essential to the aims of the VANDy-CdV project. De-identified data with linked biospecimens will be provided to VANDy-CdV members through a standardized and tracked approach. The end result of these efforts will be a carefully curated and maintained database of clinical data and biospecimens that will directly support the efforts of the VANDy-CdV team to investigate the critical role of host immunity in patients with CDI.