A Novel Developmental Process of Intestinal Epithelial Lesions in a Calf Infected with Attaching and Effacing Escherichia coli.

Abstract

ABSTRACT. A comparative study on the adhesion of attaching and effacing Escherichia coli (AEEC) to the enterocytes between the colon of a calf and the jejunum of a piglet showed differences in the developmental process of attaching and effacing (AE) lesions. In the calf, pedestals consisted of fused microvilli, while in the piglet they developed from the apical epithelial cell membranes after effacing microvilli. Microvilli adjacent to the AEEC attachment site were atrophic in the calf, whereas they were elongated in the piglet. The production of AE lesions in the calf may be indicative of a novel developmental process with AEEC infection. -KEY WORDS: attaching and effacing Escherichia coli, calf, swine.J. Vet. Med. Sci. 59 (5): [401][402][403] 1997 and O103, respectively. Intestinal specimens obtained from the calf and piglet were fixed in 20% neutral buffered formalin. After washing with 0.1 M phosphate buffer, the specimens were also fixed in 1% osmium tetroxide and then embedded in the Epoxy resin. Ultrathin sections were stained with uranyl acetate and lead citrate and were examined with a transmission electron microscope (JEOL, JEM-1010).In the colon of the calf, AEEC bacteria were attached to the apical portion of microvilli, but not observed among microvilli. Microvilli fused with one another at the sites of AEEC attachment. The pedestals were formed by degenerated microvilli. Accumulations of dense fibrillar materials were observed in the pedestals (Fig. 1).In the jejunum of the piglet, AEEC organisms were observed among microvilli, and the microvilli to which Attaching and effacing Escherichia coli (AEEC) is one of enteropathogenic E. coli (EPEC). It colonizes the intestinal tract and adheres intimately to the enterocytes, resulting in the effacement of microvilli and formation of pedestals [3]. Although there have been many reports on attaching and effacing (AE) lesions in several species with AEEC infection [4][5][6], only one report dealt with the developmental process of AE lesions [2]. We investigated AE lesions on the enterocytes in a one-month-old calf and a piglet, and we found the developmental process of AE lesions in the calf was different from that in the piglet.AEEC organisms were observed microscopically in the colon of the calf and the jejunum of the piglet in sections stained with hematoxylin and eosin. The results of immunohistochemical investigation confirmed that AEEC in the calf and piglet belonged to serogroups E. coli O111

Attaching-effacing Bacteria in Animals

“…Naturally occurring AE lesions have been reported most commonly in the large intestine (Hall et al, 1985(Hall et al, , 1988bMoxley and Francis, 1986;Mainil et al, 1987;Janke et al, 1989Janke et al, , 1990Iijima et al, 1990;Wada et al, 1994Wada et al, , 1997Holland et al, 1999b;Pearson et al, 1999) or large and small intestines, with the small intestinal lesions often confined to the ileum (Pospischil et al, 1987;Hall et al, 1988b;Schoonderwoerd et al, 1988;Janke et al, 1989Janke et al, , 1990Pearson et al, 1989;Holland et al, 1999b;Gunning et al, 2001). Cases in which AE lesions are confined to the small intestine are less common (Janke et al, 1989(Janke et al, , 1990.…”