Infection from a razor??? Do you know if your friend is using a DE? I honestly can't say that I have ever heard of this happening.
After each shave, I spray my razor down with some 70% iso alcohol. This probably kills off bacteria, but my motivation to do it is more about reducing soap scum build up and making sure the razor dries quickly.
-- Sal -- Razors don't shave people. People shave people!
There are 3 critical types of life moments: Times when we should be enamoured of the finer details, and times we should ignore the minutia.