There are pros and cons on this. When I was a child and would get strep throat, my pediatrician would prescribe antibiotics for my mom and dad too as my germs were so strong, LOL, they still are. It did not hurt them any and they did not get my strep. So, I think it is all up to the individual. Immunity usually develops if you take something for a long period. I would ask your doctor if you are concerned about this however.
Enjoy your trip.
I wouldn't, I have never heard of a doctor prescribing it as a preventative measure. They can develope immunity to the drugs effectiveness. This is why most doctor will not give it out unless they are sure the person has a bacterial infection.