Experimental infection of neonatal pigs with CNF toxin-producing strains of Escherichia coli

Wray, C.; Piercy, D.W.T.; Carroll, PJ; Cooley, W. A.

doi:10.1016/0034-5288(93)90125-y

Cited by 23 publications

(20 citation statements)

References 10 publications

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“…The invasive character seem to be a specific property of the NTEC2 strains, as testified by the absence of strains 25KH09 and of contaminating K99 þ E. coli in internal organs of calves C3 to C5, although not an exclusive one since non-NTEC E. coli were also isolated from internal organs of three calves (C5, C6, and C12). These observations are in general agreement with observations in piglets inoculated with NTEC1 strains, showing the predilection for the lung associated in some cases with diarrhoea, respiratory signs and death (Wray et al, 1993;Fournout et al, 2000;Clement et al, results not published).…”

Section: Discussionsupporting

confidence: 91%

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Necrotoxigenic Escherichia coli type-2 invade and cause diarrhoea during experimental infection in colostrum-restricted newborn calves

Bost

Roels

Mainil

2001

Veterinary Microbiology

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There exists experimental evidence that necrotoxigenic Escherichia coli (NTEC) strains producing the cytotoxic necrotising factor 1 cause intestinal and extra-intestinal disease in piglets. On the other hand, no experimental model has been developed with NTEC strains producing the cytotoxic necrotising factor 2. In all, 14 colostrum-restricted calves were orally challenged with two strains isolated from the faeces of a diarrheic calf (B20a) or from the heart blood of a septicaemic calf (1404). All calves had diarrhoea which lasted until euthanasia in eight of them. In those calves, diarrhoea was correlated with the faecal excretion of the challenge strains. At necropsy, vascular congestion of the intestinal mucosa, hypertrophy of the mesenteric lymph nodes (MLN) and some congestion of the lungs were observed. Bacteriology confirmed the colonisation of the intestine by the challenge strains which were also recovered from the heart blood, the lungs and/or the liver. Histological sections confirmed enterocolitis, lymphadenitis and limited bronchopneumonia. In the intestinal tissue sections, bacteria testing positive in an in situ DNA hybridisation assay with a CNF2 probe were observed. Those results were confirmed by immunohistochemistry with a polyclonal anti-O78 and a monoclonal anti-F17b antisera. Three of the five control calves receiving either saline or a CNF À , F17a strain (25KH09) had no clinical signs or lesions. The other two presented a profuse liquid diarrhoea but those calves were positive for the presence of K99 þ E. coli. In this model, both NTEC2 strains were thus, able to colonise the intestine, to cause long-lasting diarrhoea and to invade the blood stream with localisation in various internal organs in colostrumrestricted conventional newborn calves. #

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Section: Discussionsupporting

confidence: 91%

“…All the lambs developed severe clinical signs starting 6 h after inoculation, which consisted mainly in neurological signs and mucoid diarrhoea. Orally-inoculated NTEC1 strains also cause enterocolitis and bacterial colonisation of the lungs in piglets (Wray et al, 1993;Clement et al, results not published).…”

Section: Introductionmentioning

confidence: 99%

Necrotoxigenic Escherichia coli type-2 invade and cause diarrhoea during experimental infection in colostrum-restricted newborn calves

Bost

Roels

Mainil

2001

Veterinary Microbiology

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“…The results of this and other studies (Blanco et al., 1993, 1998; Wray et al., 1993; Burns et al., 1996) indicate that CNF2‐producing NTEC are widespread among healthy cattle. A low virulence of NTEC2‐positive strains for calves was suggested by De Rycke et al.…”

Section: Discussionsupporting

confidence: 71%

Characterization of NecrotoxigenicEscherichia coli(NTEC) Strains Isolated from Healthy Calves in Poland

Osek¹

2001

Journal of Veterinary Medicine, Series B

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Faecal samples from 132 healthy, 4±8-week-old calves from four different farms were examined for necrotoxigenic Escherichia coli (NTEC) producing the cytotoxic necrotizing factors type 1 (CNF1) and type 2 (CNF2). CNF2 genes were detected by polymerase chain reaction in 24 (6.1%) of the 396 E. coli strains tested; these strains were found in 18 (13.6%) calves used in the study. None of the 396 E. coli isolates examined possessed the gene encoding CNF1. Overall, 28.8% of E. coli examined expressed the F17 ®mbrial antigen. A strong association between CNF2 toxin and F17 ®mbriae was found (62.5% of CNF2-positive strains were F17-positive). Moreover, six out of 24 NTEC strains had the Stx1 or the Stx2 shiga toxin genes, and three additional isolates possessed the eae genetic marker of the intimin protein.

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“…CNF toxins are lethal when administrated intravenously to mice or sheep and are dermatonecrotic when inoculated into the rabbit skin (13)(14)(15). In addition, experimental oral inoculation of neonatal calves and pigs has shown that CNF-positive E. coli causes septicemia and enteritis (57,73). S. Clément, B. MartineauDoizé, I. P. Oswald, E. Oswald, M. Odin, and J. M. Fairbrother (submitted for publication) have also examined the dynamics of infection of CNF1-producing E. coli in experimentally inoculated conventional piglets of various ages and immune or weaning states.…”

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Lack of a Role of Cytotoxic Necrotizing Factor 1 Toxin fromEscherichia coliin Bacterial Pathogenicity and Host Cytokine Response in Infected Germfree Piglets

Fournout

Dozois²,

Odin

et al. 2000

Infect Immun

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Some Escherichia coli strains isolated from intestinal or extraintestinal infections in pigs produce cytotoxic necrotizing factor 1 (CNF1). In order to analyze the role of CNF1 in the pathogenesis of porcine colibacillosis, newborn colostrum-deprived germfree piglets were orally inoculated with a wild-type CNF1-producing strain (M623) or with an isogenic cnf1 mutant (M623⌬CNF1). The two isogenic strains induced a high mortality with similar lung and serosal inflammatory lesions, indicating that both strains were pathogenic in these piglets. Bacterial counts in various organs of inoculated piglets revealed an intestinal predisposition of M623 and M623⌬CNF1 strains for the cecum and colon. Extraintestinal organs (lungs, liver, spleen, and kidney) were also colonized by both strains. Similar colonization of intestinal and extraintestinal tissues in animals inoculated with either strain was observed, except in the ileum, where M623 showed a higher colonization than M623⌬CNF1. Intestinal (ileum and colon), extraintestinal (lung and kidney), and immune (mesenteric lymph nodes and spleen) tissues were sampled at 1 day postinoculation and analyzed for cytokine expression by a reverse transcriptase PCR technique. Inoculation with E. coli M623 induced an enhanced expression of inflammatory cytokines (interleukin-1␣ [IL-1␣], tumor necrosis factor ␣, and IL-12p40) in the intestinal organs compared to uninoculated piglets or piglets inoculated with nonpathogenic intestinal E. coli 862B, which is also able to colonize the intestinal tract. There was little difference in cytokine transcript levels in the intestinal and extraintestinal organs in piglets inoculated with E. coli strains M623 or M623⌬CNF1, except in the ileum, where IL-1␣ and IL-8 mRNA levels correlated with bacterial colonization. Expression of regulatory cytokines (gamma interferon and IL-4) was weak in immune tissues from piglets inoculated with M623 or M623⌬CNF1. Taken together, our data indicate that the CNF1-producing strain, M623, is pathogenic and induces inflammatory cytokine expression in germfree, colostrum-deprived piglets. Nevertheless, in this model, the CNF1 toxin does not appear to be a major factor for pathogenicity or cytokine response, as demonstrated by the use of an isogenic cnf1 mutant.

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Experimental infection of neonatal pigs with CNF toxin-producing strains of Escherichia coli

Cited by 23 publications

References 10 publications

Necrotoxigenic Escherichia coli type-2 invade and cause diarrhoea during experimental infection in colostrum-restricted newborn calves

Necrotoxigenic Escherichia coli type-2 invade and cause diarrhoea during experimental infection in colostrum-restricted newborn calves

Characterization of NecrotoxigenicEscherichia coli(NTEC) Strains Isolated from Healthy Calves in Poland

Lack of a Role of Cytotoxic Necrotizing Factor 1 Toxin fromEscherichia coliin Bacterial Pathogenicity and Host Cytokine Response in Infected Germfree Piglets

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