In my experience, giving a chameleon an antibiotic for mouth rot without debriding the area doesn't work. It just comes back. It comes back often even when it is debrided. If not treated properly, mouth rot spreads to other facial areas and may even go through the chameleon's system.
Chameleon "pus" is almost the texture of cottage cheese and the antibiotic doesn't seem to penetrate it.
All the chameleons that I had the experience with were WC and maladaption syndrome and immune system depression likely played a part. Animals bred in captivity don't seem to get it as often and by many its considered to be husbandry-related/secondary.
Also, giving an antibiotic without having done a culture/test to see what bacteria you are trying to kill wll only work if you happen to hit an antibiotic that works on the bacteria involved. Do you have the experience needed to figure out the dosage anyhow?