C. difficile diarrhea is largely a nosocomial disease and is the most frequent cause of diarrhea in hospitalized patients. Its occurrence in the outpatient setting, other than in patients confined to nursing homes, is much less common.
Darwin had arrived at a complete theory of evolution by 1839, but it was to be another 20 years before he published his ideas of evolution through natural selection in his epochal book On the Origin of Species by Means of Natural Selection.
The theory of evolution, formalized by Charles Darwin, is as much theory as is the theory of gravity, or the theory of relativity. Unlike theories of physics, biological theories, and especially evolution, have been argued long and hard in socio-political arenas. Even today, evolution is not often taught in primary schools. However, evolution is the binding force of all biological research. It is the unifying theme.