Genus Serratia presents special problems of identification because of biochemical and morphological similarity to other genera of the Enterobacteriaceae, notably Klebsiella and Enterobacter. Serratia liquefaciens is an opportunistic pathogen which is capable of colonizing a wide variety of surfaces in water, soil, the digestive tracts of rodents, plants, insects, fish, and humans. While the interaction of R. equi with epithelial cells has been studied, little is known about its interactions with phagocytic cells. The picture shows an immunofluorescence image of S. liquefaciens (in red, merged image right panel) destroying a binucleated macrophage (merged image left panel), that shows filopodial fragmentation and cell detachment. Following infections of S. liquefaciens strains on murine macrophages, cells were washed and fixed. After fixation, cells were permeabilized. Atto-488 phalloidin (Sigma), which binds polymerized F-actin, was used to identify actin filaments and fibers in eukaryotic cells. Preparations were mounted in Fluoroshield- mounting medium containing DAPI (Sigma Aldrich) and examined by epifluorescence microscopy using a Zeiss Axiovert 200 Microscope. Digital images were acquired using a Zeiss AxioCamHRc digital camera and merged using Photoshop CS3 (Adobe) software.
Credit: Remuzgo Martinez, Sara
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