Does anti-matter exist?

Anti-matter has been produced in labs. It's hard to produce in large quantities, so as far as I know, we haven't tested how it behaves thermodynamically, and we probably won't be able to for a long time, although I think we have tested it for gravity, and it falls the same direction normal matter does. As for using it as medicine, definitely not. Antimatter is annihilated as soon as it touches any normal matter, so it would be gone before it reached the infection. Even if you did get it into contact with the infection, both the matter and the antimatter are turned into huge amounts of energy, which would damage a large part of the body if it was small enough and messily destroy the patient if it wasn't. It would be like using tiny nuclear bombs as medicine.