Studies of the Human Microbiome in Clinical Center Patients

Background: \- The intestines, mouth, and skin all contain billions of bacteria and some fungi. Every person s body contains microorganisms like these. They normally do not make people sick. Researchers are interested in how these microorganisms change when a person is hospitalized. They want to find out if changes take place because of the hospitalization (such as treatments used or changes in medical condition) or because of a person s biology (such as their immune system). Objectives: \- To understand which microorganisms are most likely to spread through hospitals and what affects that spread. Eligibility: \- People 2 years of age and older who are going to be inpatients at the National Institutes of Health Clinical Center (NIHCC) for at least 48 hours. Design: * Clinicians will take samples from participants up to once a day for as long as they are hospitalized at NIHCC. * Samples will be taken with a swab, from the rectal area, groin, throat, and armpit, and possibly other areas. * Participants may give a stool sample or be asked to spit into a cup. * Clinicians will collect some information from participants medical records. They may request some samples of tissue that are left over from procedures already scheduled at NIHCC. * After participants leave the NIHCC, samples may be taken when they return for follow-up visits from their hospitalization, for up to 2 years. They will not have to return as a follow-up for this study only.

* INCLUSION CRITERIA: Individuals must meet the following inclusion criteria to participate in the study: * Be inpatients in the NIH CC with an expected hospitalization of at least 48 hours beyond the date of referral. * Be 2 years of age or older * Allow storage of tissue samples for future analyses. * Allow genetic testing of body fluids, and tissue specimens. EXCLUSION CRITERIA: A patient will not be eligible if he/she has any condition which, in the investigator s opinion, places the patient at undue risk by participating in the study.