As with any animal, please clean the area with warm water and soap! Soap up the nose is the most unpleasant thing in the world, trust me, but our beloved pets aren't as sanitary as we are. This statement isn't aimed at just rats, but at our cats and dogs too. If a cat or dog scratched me, I'd still clean the wound out. I also just have sensitive skin/immune system and washing the affected area can minimize the chance for a reaction.
If you're worried about those illnesses and diseases that pet rats allegedly carry, don't let the news scare you. We'll probably hear way more about how our beloved rats may be "carrying something deadly" way more than a dog with rabies or any other illnesses dangerous to humans. Am I against the news? No. Just please take what they (and what anyone says) with a grain of salt. I very rarely see news articles about how rats are wonderful, lovely little companion animals. The articles I see all the time are them as vermin, disease-carriers, etc, which is not true.
Fun fact! There is currently debate on whether or not it was GERBILS that caused the Black Death, and not our bald-tailed furbabies. Dunno if that was ever proven or not.