A diagnostic device as a first electrode formed by a noble metal that is not attackable by acid, and a second electrode that is formed of silver. The first and second electrodes are at least partially immersed in a nutrient solution contained in a container, into which a tissue sample can be introduced. An electrical voltage is applied between the first and second electrodes, and a change in an electrical variable between the electrodes is measured when ammonia is present. The diagnostic device allows fast screening of tissue samples for Helicobacter pylori.
