Dr. Greene’s Answer:
Washing the hands with regular soap and water temporarily eliminates some of the body’s good germs while it gets rid of the bad germs. The same is true when using an alcohol-based hand sanitizer. However, in both cases, the body quickly replenishes the good germs on the hands – often moving them in from just up the arms (where there are fewer harmful germs). So there is no harm in using regular soap or alcohol-based products. In fact, regular hand cleaning improves the proportion of “good germs” on the hands.
There is no risk of antibacterial resistance when using regular soap or alcohol-based products. The alcohol in sanitizers evaporates quickly and completely, leaving no residue behind to which organisms could adapt. Some scientists are concerned the ingredients in antibacterial soap, though, may cause resistance. (Aiello et al: Consumer antibacterial soaps: effective or just risky? Clin Infect Dis, 2007).