I work out there often and I enjoy two immodium instants with my cornflakes every day and then lots of post dinner (back at hotel) sweet stuff and it works a charm.
This appears to be seriously bad health advice. Work it might. Good for you?....
Immodium, or any other "stopper", should be used as a last resort if you have to travel with the trots.
Definitely shouldn't be taken as a preventative.
What the body wants to expel, should be expelled.
I'd go with the yoghurt/sensible food hygiene/charcoal type posts above.
Definitely would not take antibiotics, unless required after the fact. You'll just wreck your internal flora.