Ultrastructural Analysis of Bacteria–Host Cell Interactions - Bacterial Pathogenesis: Methods and Protocols - page 163

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Ultrastructural Analysis of Bacteria-Host
Cell Interactions
David W. Dorward
Summary
Electron microscopy of bacterial pathogens and interactions between bacteria and host
cells and tissues provides valuable insights into structural and molecular properties and
processes involved in pathogenesis. Applications for electron microscopy in bacterial
pathogenesis range from discovering etiologic agents and following chronological events
during infections by conventional examination of clinical samples to assessing molecular
host-cell responses to infection and in situ interactions between receptors and ligands using
specific immune-labeling techniques. This chapter focuses on techniques for preparing
samples of bacteria and host cells for conventional transmission (TEM) and scanning
electron microscopy (SEM) and use of luminescent nanocrystals or “quantum dots” as
specific probes for correlative light and electron microscopy. Conventional TEM and SEM
are well established tools for high resolution examination of structural effects and chrono-
logical events associated with bacterial infections. The recent development of quantum
dots as physiological and immunological probes in biology has provided a powerful
technique for bridging fluorescent analyses of fixed and live material with preparation and
examination by TEM and SEM.
Key Words: Transmission electron microscopy; scanning electron microscopy;
Gram-positive; Gram-negative; immune labeling; histochemistry; colloidal gold; quantum
dots; correlative microscopy; fluorescence.
1. Introduction
Ultrastructural analyses by TEM and SEM are versatile and integral
tools for examining and characterizing infectious cycles and host responses
to bacterial pathogens at the tissue, cellular, sub-cellular, and molecular
levels. Utilizing focused electron beams with wavelengths less than 100 pm,