The present invention relates to a polymer coating comprising a) one or more polymers, said polymers comprising a first cleavage site and b) a diagnostic agent that is non-covalently bound within the polymer coating, said diagnostic agent being releasable from said coating upon cleavage of said first cleavage site, the first cleavage site being cleaved by an enzyme specifically provided by a microbe belonging to a first group consisting of a limited number of microbial strains, species or genera, and not cleaved by any enzyme provided by any microbe not belonging to said first group, wherein cleavage of the said first cleavage site results in release of the said diagnostic agent from the coating, the release of said diagnostic agent being indicative for the presence of a microbe belonging to the said first group. Further, methods of preparing such a coating and methods of detecting a visualizing the presence of microbes are presented.
