Strain-level typing and identification of bacteria using mass spectrometry-based proteomics.

Because of the alarming expansion in the diversity and occurrence of bacteria displaying virulence and resistance to antimicrobial agents, it is increasingly important to be able to detect these microorganisms and to differentiate and identify closely related species, as well as different strains of a given species. In this study, a mass spectrometry proteomics approach is applied, exploiting lipid-based protein immobilization (LPI), wherein intact bacterial cells are bound, via membrane-gold interactions, within a FlowCell. The bound cells are subjected to enzymatic digestion for the generation of peptides, which are subsequently identified, using LC-MS. Following database matching, strain-specific peptides are used for subspecies-level discrimination. The method is shown to enable a reliable typing and identification of closely related strains of the same bacterial species, herein illustrated for Helicobacter pylori .