Overview of the proteomics strategy for biomarker discovery. Abscesses of infection were microscopically identified in thin-sectioned tissues (formalin-fixed, embedded in paraffin) by histology (H&E stained) and localization of bacteria by specific antibody (IHC). The tissue sections were next examined by imaging mass spectrometry (IMS) to identify analyte masses that were localized to the selected regions of interest. Using laser-capture microdissection of select regions of the tissue sections identified by IMS and histology, a more extensive proteomic analysis could then be performed by a technique that combines the physical separation capabilities of liquid chromatography (LC) with the sensitive mass analysis capabilities of mass spectrometry (LC-MS/MS). Finally, the LC-MS/MS data was compared to masses observed by IMS for highest confidence in biomarker identification.