Fluorescent PAS-reaction study of the epithelium of normal rabbit ileum and after challenge with enterotoxigenic Escherichia coli.

Fluorescent periodic acid-Schiff reaction (FPR) was used in the study of the normal rabbit ileal epithelium and its changes after injection of living cultures or enterotoxins of enterotoxigenic Escherichia coli. This reaction, with the use of auramine OO-SO2 complex as a Schiff-type reagent, demonstrates gut epithelium periodate-reactive mucosubstances more distinctly and brightly than does the common periodic acid-Schiff (PAS) reaction. It permitted the quantitative assessment of polysaccharide content in the gut sections by microfluorimetry, and examined extensively the mucosal structures, brush border, and mucous cells which participate in the interaction with enteropathogens. Fluorescent periodic acid-Schiff reaction showed that noninvasive enterotoxigenic E. coli O148:H28 B7A organisms caused restricted damage to the intestinal epithelium brush border. Invasive enterotoxigenic E. Coli O26:K60:H11 N3 organisms penetrated the epithelium and caused extensive brush border lesions and mucous cell hyperproduction. Importance of FPR in the complex morphologic analysis of enteric infections, pathogenesis of escherichoses under study, and some aspects of the intestinal epithelium histology are discussed.