Milestones in the testing of surface disinfectants: from Robert Koch to CEN TC 216.

The first publication on testing disinfection procedures dates back to 1881 and was compiled by Robert Koch. Although his conclusions were erroneous, we continue to use the "germ carrier test" right up to the present day even if preference is now given to the suspension test first devised by Geppert. Over the years many conceptual milestones had to be reached, and much knowledge and many insights were needed to develop this procedure further to ensure reproducible results.