For some values of "destroyed", including "not destroyed, just dislodged".
Obviously, washing hands with soap and water is important and helps reduce infection. This CDC article has some information about some of the difficulties with this. (EG: Why don't surgeons shower before surgery?) When is clean too clean? (http://wwwnc.cdc.gov/eid/article/7/2/70-0225_article.htm)
Generally soap destroys bacteria through acid-base reactions with the amino acids in the bacteria. As a science experiment we took bacterial colonies we had grown and exposed them to both an anti-microbial solution and a plain soap. The anti-microbial solution causes the bacteria to die, and the soap causes them to explode.
However, in heath care institutions it is impractical to use soap repeatedly due to damage it causes to your skin (for the same reason it damages bacterial cells, it is indiscriminate). Similarly with ultraviolet light sanitizers which also work by destroying the cell material and are equally harmful to your skin and bacteria.
There is an interesting investigation going on into encapsulation, basically having health care professionals change gloves all the time which doesn't kill the microbes on their hands but gives them fresh 'skin' each glove change.
> Generally soap destroys bacteria through acid-base reactions with the amino acids in the bacteria.
I'd like to learn more about what you mean by this, since everything from my biology training has taught me that the mechanism of action of detergents is primarily disruption of the lipid membrane of bacteria--ie. causing lysis and release of cellular contents into solution[1]. The disruption is due to the amphiphilic nature of detergent molecules (they are attracted to both polar water molecules and to the non-polar lipid molecules in cell membranes, ripping the lipids away with agitation of the solution). Amphiphiles are not acid base so much as partially charge-polarized and capable of hydrogen bonding, and partially charge/hydrogen bond neutral. Attaching to lipids and water simultaneously is thermodynamically favorable for them.
It's true that bacterial S-layers are proteinaceous and provide some protection, but detergents are still effective via the above mechanism (though often more so in concert with EDTA, urea, or other agents).
Some bacteria (ex. Streptococcus pneumoniae, Klebsiella pneumoniae, some strains of E. coli) have a capsule that would provide resistance to detergents, but it is generally a structure made of polysaccharides, not amino acids (ie. polypeptide). Bacillus anthracis does have a polypeptide capsule that would serve as a barrier to detergents, but it's an unusual characteristic.
This is not to say that high or low pH (base or acid) cannot destroy bacteria, but it is not the primary mechanism of action of soap or most so called anti-microbial products. "Explode" is not quite the right word for soap (it would be for hypo-osmotic lysis buffer). It really tears holes in the cell membrane.
Some anti-microbial soaps do contain agents that inhibit bacteria through a mechanism other than lysis. Triclosan is in the anti-microbial soap commonly found in hospitals, and it inhibits fatty acid synthesis--preventing bacteria from forming cell membranes. It's typically combined with a detergent though.
Ultraviolet light sanitizers (254 nm light) knock some bonds loose in DNA, causing thymine dimers to form. This doesn't quite destroy them, but it does prevent them from replicating and can inhibit production of harmful gene products by throwing a wrench in transcription.
You're right about soap overuse being damaging to skin, and glove changes are important. One of the most simple changes I've heard suggested is a switch back to brass doorknobs, since the copper kills bacteria via the oligodynamic effect (still not very well understood).
Ok, so the acid-base explanation was the one we came up with after observing what soap did to our bacteria under a microscope. The bacteria lost cellular cohesion and became a sort of soup. In the case of anti-microbial soap the bacteria simply ceased replicating (which we interpreted as them being dead).
Our test soap was SafeGuard brand (regular soap) and an antibacterial blend of SoftSoap brand.
If you don't mind I'd like to borrow some of your explanatory text to augment and/or replace some of the material in that experiment for other home schooling parents.
Obviously, washing hands with soap and water is important and helps reduce infection. This CDC article has some information about some of the difficulties with this. (EG: Why don't surgeons shower before surgery?) When is clean too clean? (http://wwwnc.cdc.gov/eid/article/7/2/70-0225_article.htm)