All diseases are characterized by distinct changes in tissue molecular distribution. Molecular analysis of intact tissues traditionally requires pre-existing knowledge of, and reagents for, the targets of interest. Conversely, label-free discovery of disease-associated tissue analytes requires destructive processing for downstream identification platforms. Tissue-based analyses therefore sacrifice discovery to gain spatial distribution of known targets, or sacrifice tissue architecture for discovery of unknown targets. To overcome these obstacles, we developed a multi-modality imaging platform for discovery-based molecular histology. We apply this platform to a model of disseminated infection triggered by the important pathogen Staphylococcus aureus, leading to the discovery of infection-associated alterations in the distribution and abundance of proteins and elements in tissue. These data provide an unbiased, three-dimensional analysis of how disease impacts the molecular architecture of complex tissues, enable culture-free diagnosis of infection through imaging-based detection of bacterial and host analytes, and reveal molecular heterogeneity at the host-pathogen interface.