Ultrastructural changes in the small intestine of neonatal calves with enteric colibacillosis

The small intestines of calves inoculated orally with the enteropathogenic strain of Escherichia coli 0101:K'B41',K99 were examined by electron microscopy at 3, 6, 12, 16, 21, 36, 69, 70 and 72 hours after inoculation. The challenge organism adhered to the mucosa of the distal small intestine from six hours post-inoculation. Bacteria were separated from the microvillous brush border by a gap of 200 to 300 nm in which bacterial fimbriae and the microvillous glycocalyx were seen. Bacteria never were found in epithelial cells but were present in macrophages in the lamina propria from 12 hours. At three and six hours, cytopathic changes were not seen in the small intestine, but from 12 hours epithelial cells on affected villi had blunt and thick microvilli and contained cytoplasmic inclusions. Epithelial cells were seen frequently in the process of extrusion from the villi, either singly, in small groups, or as ribbons of cells. Intervillous bridges, characteristic of villous fusion, were seen frequently from 69 hours.     

Scanning electron microscopy of the small intestine of a normal unsuckled calf and a calf with enteric colibacillosis.

Sections of the small intestine were taken under general anaesthesia from a normal calf and from a calf with enteric colibacillosis and examined by scanning electron and light microscopy. In the normal calf villi were long and oval throughout the intestine and in the challenged calf there was villous stunting and fusion in the distal small intestine.     

Bovine enteric colibacillosis

In this article, the authors discusses procedures used to determine enteropathogenic strains of Escherichia coli, the history of the development of prophylactic procedures, including cow vaccination and specific monoclonal antibody, and other preventative measures with as proper management, nutrition, and sanitation.     

Protection of neonatal calves against fatal enteric colibacillosis by administration of egg yolk powder from hens immunized with K99-piliated enterotoxigenic Escherichia coli.

The protective effects of egg yolk powder prepared from hens vaccinated with heat-extracted antigens from K99-piliated enterotoxigenic Escherichia coli (ETEC) strain 431 were evaluated in a colostrum-fed calf model of ETEC-induced diarrhea caused by a heterologous strain (B44). The antibody powder was obtained by spray-drying the water-soluble protein fraction of egg yolks after removing the lipid and fatty components by precipitation with hydroxypropylmethylcellulose phthalate. A total of 16 colostrum-fed calves were studied to determine whether the orally administered antibody powder would prevent fatal bovine colibacillosis caused by a virulent ETEC strain. Clinical response of individual calves was monitored and evaluated in the context of these variables: fecal consistency score, intestinal colonization, weight loss, and mortality. Control calves that were treated with vehicle (milk with egg yolk powder from nonimmunized hens) had severe diarrhea and dehydration and died within 72 hours after infection was manifested. In contrast, calves fed milk containing egg yolk powder with antipili agglutinin titers of 1:800 and 1:1,600 had transient diarrhea, 100% survival, and good body weight gain during the course of the study. Results indicate that the orally administered egg yolk powder protected against ETEC-induced diarrhea in neonatal calves and that the protective components may have been the antibodies raised by vaccination of chickens against ETEC.     

Prenatal immunization against experimental enteric colibacillosis in piglets.

To establish a model for the study of prenatal immunization against enteric colibacillosis a proportion of the litters of seven sows were immunized in utero 18 to 22 days before term by intra-amniotic and intramuscular injection of Escherichia coli antigen and the litters challenged at birth with either homologous or heterologous strains. Protection against homologous challenge was demonstrated in some but not all vaccinated piglets. The study was severely compromised by the occurrence of intrauterine death in a significant proportion of vaccinated piglets.     

Studies on the immunity of the calf to colibacillosis--VII: the experimental reproduction of enteric colibacillosis in colostrum-fed calves.

Eight newborn calves were challenged orally with a known enteropathogenic strain of Escherichia coli 0101 K?(A) and two to six hours later each calf was fed a minimum of three pints colostrum. All calves suffered from acute diarrhoea of varying severity within 24 to 48 hours of infection. Immunofluorescent and histological examination of the small intestine demonstrated adherence of the challenge organism to the epithelium and the presence of pathological lesions similar to those seen in colostrum-deprived calves with enteric colibacillosis. It was concluded that in order to be effective prophylactically, colostrum must be fed prior to infection.     

Enterotoxigenic colibacillosis in colostrum-fed calves: pathologic changes.

Enterotoxigenic colibacillosis was experimentally produced in 8 of 9 colostrum-fed calves orally given 10(11) Escherichia coli. The eight calves developed profuse diarrhea accompanied by dehydration and depression. At 12 hours after exposure, all calves were euthanatized for necropsy and for collection of tissues for microscopic examination. Histopathologic changes included stunted villi in the jejunum and ileum, focal degeneration and exfoliation of absorptive epithelial cells at the tips of jejunal and ileal villi, and focal emigration of neutrophils which was especially prominent above the dome area of aggregated lymphatic follicles (Peyer's patches). A layer of E coli adhered to the epithelial surface of the jejunum and ileum. In the duodenum, lesions were minimal or absent and bacteria were not adhering to the mucosa. Histopathologic changes were not observed in other tissues. In two calves examined 24 hours after they were inoculated and in two calves euthanatized 24 to 36 hours after spontaneously developing enteric colibacillosis, lesions were similar to those observed in the calves at 12 hours after exposure.     

仔猪黄痢的诊断和预防

贵州省黔西县民远养殖场在 1 983年引进大约克公猪和荣昌母猪进行杂交 ,于同年 1 0月份相继产仔 ,到 1 999年已产仔 1 0 0 0多头。其中发生新生仔猪腹泻病症的约为 30 0多头 ,发病率为 30 %。该场曾用仔猪大肠杆菌基因工程苗进行预防 ,但仔猪生后仍有发病。对发病仔猪曾用痢特灵、氯霉素、红霉素、土霉素等抗生素进行治疗 ,但效果不佳 ,仍有1 2 0头死亡 ,病死率高达 40 %。本文对新生仔猪腹泻病例进行了病原的分离与鉴定 ,并取致病菌株 ,制成活菌苗 ,喂服母猪 ,有效地控制了该场新生仔猪腹泻的发生。报告如下。1　流行病学及临床症状该病主…     

Vaccination of the dam by the intramuscular or deep subcutaneous route to prevent neonatal calf enteric colibacillosis.

Comparison of colostrum-induced immunities in calves was made by challenge exposure with Escherichia coli. These calves were delivered of cows which were vaccinated intramuscularly or deep subcutaneously (in the region of the mammary lymph nodes) with strain B44 E coli bacterin during the last trimester of pregnancy. The calf of each cow was allowed to nurse colostrum naturally after birth. Cows vaccinated by either route of administration were capable of providing increased resistance to their calves, via the colostrum, when compared with nonvaccinated cows.     

山羊大肠杆菌病的诊治

1999年 8～ 9月 ,深圳龙岗区南澳镇某羊场发生运输到点羔羊和青年羊的大肠杆菌病 ,主要表现为呼吸急促和轻度腹泻。经我们调查、诊断和治疗 ,取得满意效果。报告如下。1　情况调查该场属新建 ,1999年 7月 18日从贵州省某地运进羊 2 80只 ,运输途中死亡羊 5 3只 ,运输到点后死亡