The biologic samples (organism) will be under the control of the principal investigator of this research project. To protect confidentiality, all personal identifiers (i.e., name, social security number, and birth date) will be removed (de-identified) and replaced with a specific code number. The information linking these code numbers to the corresponding subjects' identities will be kept in a separate, secure location. The investigators on this study will keep the samples indefinitely. The biologic samples will be provided to Dr. Curtis Donskey, Case Western Reserve University, Cleveland, Ohio. Dr Donskey will perform colony counts on the samples in order to determine the density of organisms in the sample, using methods he described in work he published in the New England Journal of Medicine (11). All samples will be provided de-identified. Dr Paterson will perform pulsed field gel electrophoresis on the isolates to determine if isolates are genotypically identical between baseline and post-SDD. If a subject withdraws and provides the request in writing, samples collected and not already processed will be destroyed. All samples will be kept in Dr Paterson's laboratory in Scaife Hall, Room 812, 3550 Terrace Street or in Donskey's laboratory at the Cleveland Veterans Affairs Medical Center, East Avenue, Cleveland OH.