Compositions for prevention and treatment of microbial infections, such as microbial infections that comprise a biofilm, or a microbe that is capable of forming a biofilm are described. The compositions comprise an enzyme that is able to convert a substrate to release hydrogen peroxide and a substance that includes a substrate for the enzyme. The enzyme is additional to any enzyme activity able to convert the substrate to release hydrogen peroxide that may be present in the substance. The substance may be an unrefined natural substance or a substance that includes a purified substrate for the enzyme.
