The imaging of intracellular pathogens inside host cells is complicated due to low resolution and sensitivity of conventional fluorescence microscopy and the lack of ultrastructural information. Here we present a new method to visualize pathogenic bacteria during infection that circumvents these problems. By using a metabolic hijacking approach the intracellular pathogen Salmonella Typhimurium was bio-orthogonally labelled in a stochastic optical reconstruction microscopy (STORM) and correlative light electron microscopy (CLEM) compatible manner, allowing the imaging of the Salmonella-pathogen within the ultrastructural cellular context of its host cell with a resolution of 20 nm. This STORM-CLEM approach represents a new tool to understand the lifecycle of pathogenic bacteria during host cell invasion.
Daphne M. van Elsland, Sílvia Pujals, Thomas Bakkum, Erik Bos, Nikolaos OikonomeasKoppasis, Ilana Berlin, Jacques Neefjes, Annemarie H. Meijer, Abraham J. Koster, Lorenzo Albertazzi and Sander I. van Kasteren. ChemBiochem 10.1002/cbic.201800230