[iamelgringo]

There are substances that are bacteriostatic, which mean that they retard the growth of bacteria. Sterile water is actually bacteriostatic, because there is no food for the bacteria to grow in.

Silver and other heavy metals are bacteriostatic as well. Other substances are bactericidal, which means that they actively kill bacteria.

Antibiotics are bactericidal. You don't want to take antibiotic or bactericidal substances on a regular basis, because you end up putting unnecessary evolutionary selection pressure on your normal bacterial flora. That is, you don't want to kill all the good bacteria, otherwise the bad ones will overpopulate because they have no competition.

I'm guessing that the crocs aren't bactericidal, they are probably baceriostatic.