My brother kissed my red eared slider turtle. what is the infection risk?

Hard to say: Turtles are a known source of several germs that could trigger problems with your brother.E coli & salmonella travel into the intestines and can set off significant diarrhea, enough to require medical attention. The turtle likely will not suffer from your brothers germs. They live among worse. Sometimes brotheers need to learn things the hard way.If he gets sick it serves as a learning opportunity