Field Emission Scanning Electron Microscopy of the Interaction of Clostridium difficile with Human Embryonic Intestinal Cells.

摘要

An in vitro assay system, consisting of monolayers of human embryonic intestinal cells (HEI) and Clostridium difficile (C. difficile), was used to observe interactions of microorganisms with the cell surface and cytoplasm. Tests were performed using Toxin B positive C. difficile Strain 938, and Toxin B negative Strain 789, harvested from casamino acids agar (CAS), and CAS-containing subinhibitory concentrations of clindamycin (CAS-CL). Adherence to the surface and internalization into HEI cells was quantified at 30, 60, and 90 min. Cryopreserved and freeze fractured preparations were made at 60 min and observed for adherence and internalization using field emission scanning electron microscopy. Quantitative micro-organism determinations, confirmed by the observed micro-organism activity harvested from CAS and CAS-CL, revealed their capability to adhere to and/or enter HEI cells. The Toxin B producer, Strain 938, harvested from CAS-CL entered the cytoplasm and remained intact within it.