Investigating Bacterial Pathogen-host Interaction by Using Scanning Electron Microscopes and Transmission Electron Microscopes

Electron microscopes have been widely used to investigate cell structures under high resolution. A scanning electron microscope (SEM) provides tridimensional images of a cell surface, while a transmission electron microscope (TEM) is commonly employed to observe the internal structure changes of host cells after bacterial adherence and invasion. The SEM and TEM can reveal bacterial location, binding patterns, and host cell structure changes/damages under high resolution. The normal intestinal epithelial cells constitute a physical barrier to prevent microorganisms from entering the bloodstream. Intracellular bacterial pathogens including Campylobacter jejuni have specific tissue adherent and invasive capabilities, and can breach the barrier, and cause human gastroenteritis and other diseases. Our EM study demonstrates unique bacterial adherence, invasion, early endocytosis, and transcellular transcytosis in human intestinal cells. Although numerous molecular biological methods have been developed, electron microscopes are still valuable tools to study the bacterial pathogen-host interaction. This chapter will present an overview of the uses of the SEM and TEM to investigate the interaction of Campylobacter jejuni and human intestinal cells, and also introduce our specimen preparation procedures for the SEM and TEM observation. Our study demonstrates that the combination of scanning electron microscopy with transmission electron microscopy can provide precise and detailed information for understanding bacterial pathogen-host interaction.