Phage therapy reduces Campylobacter jejuni colonization in broilers   总被引：1，自引：0，他引：1  

Wagenaar JA  Van Bergen MA  Mueller MA  Wassenaar TM  Carlton RM 《Veterinary microbiology》2005,109(3-4):275-283

The effect of phage therapy in the control of Campylobacter jejuni colonization in young broilers, either as a preventive or a therapeutic measure, was tested. A prevention group was infected with C. jejuni at day 4 of a 10-day phage treatment. A therapeutic group was phage treated for 6 days, starting 5 days after C. jejuni colonization of the broilers had been established. Treatment was monitored by enumerating Campylobacter colony forming units (CFU) and phage plaque forming units (PFU) from caecal content. Counts were compared with control birds not receiving phage therapy. A clear 3 log decline in C. jejuni counts was initially observed in the therapeutic group, however, after 5 days bacterial counts stabilized at a level 1 log lower than that of the control group. Colonization of C. jejuni in the prevention group was delayed by the treatment and after an initial 2 log reduction, colonization stabilized within a week at levels comparable to the therapeutic group. The CFU and PFU counts displayed opposing highs and lows over time, indicative of alternating shifts in amplification of bacteria and phages. There were no adverse health effects from the phage treatment. Two different phages were combined as therapeutic treatment of Campylobacter positive chickens challenged at the age approaching broiler harvest. This again resulted in a significant decrease in Campylobacter colonization. We conclude that phage treatment is a promising alternative for reducing C. jejuni colonization in broilers.  相似文献   

Vacuolating cytotoxin produced by avian pathogenic Escherichia coli   总被引：2，自引：0，他引：2  

Salvadori MR  Yano T  Carvalho HE  Parreira VR  Gyles CL 《Avian diseases》2001,45(1):43-51

The purpose of this study was to determine whether avian pathogenic Escherichia coli produced cytotoxic activity. Culture supernatants of 20 E. coli strains isolated from cellulitis lesions in chickens, five E. coli strains from avian septicemia, five from swollen head syndrome, and five from the feces of healthy chickens were incubated with primary chicken embryo fibroblast (CEF) cells, primary chicken kidney (PCK) cells, a quail fibroblast cell line (QT-35), and four mammalian cell lines (human epithelioid cervical carcinoma, African green monkey kidney, Chinese hamster ovary, and human larynx epidermoid carcinoma). Cytotoxicity was observed with supernatants from the 30 avian pathogenic strains on the two primary chicken cells (CEF and PCK). The highest dilution of culture supenatant that induced cytotoxic changes in 50% of the cells was 1/64. Supernatants from the five strains from normal feces were noncytotoxic, and none of the supernatants was cytotoxic for the QT-35 or the four mammalian cell lines. The cytotoxic effect, which was observed as early as 2 hr after exposure of the cells, was maximal at 6 hr and was evident as vacuolation, morphologically indistinguishable from that previously reported for culture supernatants of Helicobacter pylori. Like the activity in H. pylori, the cytotoxicity of the avian pathogenic strains was destroyed by heating at 70 C for 30 min and by exposure to proteolytic enzymes and was retained by filtration with a 100,000 molecular weight cut-off ultrafilter. Supernatants of two vacuolating cytotoxin-positive cultures of H. pylori failed to induce vacuolation of the CEF and PCK cells but caused the characteristic vacuolation in HeLa and Vero cells. The observations suggest that avian pathogenic E. coli produce a cytotoxin that is similar to the cytotoxin of H. pylori but may be specific for avian cells.  相似文献   

The role of K antigens of enteropathogenic Escherichia coli in colonization of the small intestine of calves.   总被引：8，自引：2，他引：6       下载免费PDF全文

J J Hadad  C L Gyles 《Canadian journal of veterinary research》1982,46(1):21-26

The colonizing and proliferating abilities of enterotoxigenic acapsular or K99- mutants of bovine enteropathogenic Escherichia coli strains were compared with those of their capsulated and K99+ parent strains in the small intestine of infected colostrum-fed calves. Calves infected with the enteropathogenic E. coli parent strains developed profuse diarrhea and severe dehydration. None of the calves which received the acapsular mutant developed diarrhea and one of three calves inoculated with the K99- enterotoxigenic mutant developed moderate diarrhea. The parent enteropathogenic E. coli strains colonized the middle and lower small intestine; in these areas a layer of specific immunofluorescence against the enteropathogenic E. coli covered most villi and 80% of the organisms were associated with the intestinal wall. The acapsular mutant strain failed to colonize the small intestine and fluorescent bacteria were not observed in any area of the small intestine. The K99- mutant proliferated to a lesser extent than did the K99+ parent strain in all areas of the small intestine but moderately colonized the lower small intestine where fluorescent bacteria were observed to cover parts of the intestinal villi.  相似文献   

Bacterial infection and immunity in domestic animals: J.B. Woolcock. Elsevier Scientific Publishing Company,Amsterdam, 1979, 254 pp., Can. $ 75, Dfl. 135/US$ 65.75, ISBN 0-444-41768-0     

Carlton L. Gyles 《Veterinary microbiology》1981,6(2):171-172

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Limitations of the Infant Mouse Test for Escherichia coli Heat Stable Enterotoxin   总被引：9，自引：1，他引：8       下载免费PDF全文

C. L. Gyles 《Canadian journal of veterinary research》1979,43(4):371-379

A study was undertaken to evaluate the response of different test systems to preparations of heat-stable enterotoxin (ST) derived from Eschericihia coli strains recovered from diarrheal disease of humans, pigs and calves. Sterile broth culture supernatants of enterotoxigenic strains of E. coli were heated at 65°C for 30 minutes and tested for the presence of heat-stable enterotoxin. Three test systems, namely, ligated intestine of weaned pigs, ligated intestine of rabbits and the infant mouse test were used in attempts to detect ST in the culture supernatants. Two patterns of reaction were observed in response to ST-containing preparations: either the preparation elicited a response in the three tests or the preparation elicited a reaction only in the ligated pig intestine. A response in all three tests were observed for 5/5 human ST-producing E. coli, 5/5 bovine enterotoxigenic E. coli, 5/5 “atypical” porcine enterotoxigenic E. coli, 3/3 St⁺LT^- porcine E. coli of serogroup O138:K81 and 4/24 LT⁺ST⁺ porcine E. coli. A response only in the ligated pig intestine was obtained with 5/5 ST⁺LT^- porcine E. coli belonging to serogroups other than O138:K81 and to 20/24 ST⁺LT⁺ E. coli from pigs. The results are consistent with the view that there are two kinds of ST, one of which (ST1) reacts in all three tests and the other (ST2) which reacts only in the ligated pig intestine. The findings underscore the limitations of the infant mouse test as a means of detecting ST in porcine isolates of E. coli, since the test fails to detect ST produced by a large number of these E. coli strains. There appeared to be a relationship between kind(s) of ST produced and the animal species from which the producing organism was recovered.  相似文献   

Ultrastructural ocular lesions of 6-aminonicotinamide toxicosis in rabbits     

J A Render  J J Turek  E J Hinsman  W W Carlton 《Veterinary pathology》1985,22(5):475-482

6-Aminonicotinamide, given by intraperitoneal injection to male and female Dutch belted rabbits, produced swelling and vacuolation of ciliary and iridal epithelium plus vacuolation of the retinal pigment epithelial and outer plexiform layers of the retina. By transmission electron microscopy, inner and outer ciliary epithelial cells and inner iridal epithelial cells contained numerous coalescing, membrane-bound vacuoles of the cytocavitary network. These vacuoles were viewed as numerous interconnecting, intracytoplasmic cavities in scanning electron micrographs. Swelling of vacuolated epithelial cells and the presence of fibrin and proteinaceous fluid in the ciliary stroma resulted in thickening of the anterior ciliary processes with the formation of surface alterations detectable by scanning electron microscopy. In transmission electron micrographs the vacuoles in the retinal pigment epithelium were large, electron-lucent spaces and the vacuoles in the outer plexiform layer of the retina appeared to be intracytoplasmic spaces in axons of photoreceptor cells. Distention of cytocavitary structures has been reported in glial cells of animals given 6-aminonicotinamide and this change was apparently due to alterations in ion and water movement across cellular membranes that resulted in intracellular edema.  相似文献   

The effect of antisera on porcine enteropathogenic Escherichia coli in ligated segments of pig intestine.          下载免费PDF全文

C C Enweani  C L Gyles    D A Barnum 《Canadian journal of veterinary research》1975,39(1):46-53

Nineteen antisera produced in pigs against 14 enteropathogenic and five nonenterotoxigenic porcine strains of Escherichia coli were tested for their ability to inhibit gut loop fluid accumulation induced by homologous and heterologous organisms. In addition, four antisera produced in pigs by an intensive series of intravenous inoculations and three by a less intensive series of intramuscular injections of a polyvalent E. coli vaccine were evaluated. Antisera were also produced in rabbits against eight strains of porcine enteropathogens and tested in pig gut loops. Fluid inhibiting activity was detected in prevaccinal sera of pigs but not of rabbits. This activity was significantly increased following immunization. When single strains of E. coli were used for immunization the activity of the antisera against heterologous organisms varied considerably from one test strain to another and was usually much less than that against the homologous organism. The activity against heterologous organisms could not be associated with relatedness of the O, K and H antigens of the vaccine and the test strains. Antisera produced against a vaccine made by combining three strains were shown to exert inhibitory effects on heterologous organisms similar to those against homologous organisms. Considerably less activity against homologous and heterologous organisms was present in antisera produced by the series of intramuscular compared with the series of intravenous injections.  相似文献   

Immunohistochemical staining for S100 protein in the diagnosis of canine amelanotic melanoma     

G E Sandusky  W W Carlton  K A Wightman 《Veterinary pathology》1985,22(6):577-581

Formalin-fixed, paraffin-embedded tissue samples of canine amelanotic melanomas and normal canine tissues were studied immunohistochemically for the presence of S100 protein. Use of the avidin-biotin complex procedure demonstrated variable amounts of S100 protein in the tumor cell cytoplasm and nuclei in 26 of 31 tumors. S100 protein was not observed in some other common canine skin tumors stained by the avidin-biotin complex technique. These were a mast cell tumor, fibrosarcoma, mammary gland adenocarcinoma, histiocytoma, transmissible venereal tumor, and a thyroid gland adenocarcinoma. Among normal tissues the presence of S100 protein was demonstrated in chondrocytes in the trachea, myoepithelial cells in the breast, melanocytes in the skin, some sweat glands and ducts in the skin, stellate cells in the pituitary, and interdigitating reticulum cells in the lymph node and in Peyer's patches. These results indicate that the avidin-biotin complex procedure for demonstrating S100 protein is a useful diagnostic tool in the diagnosis of canine amelanotic melanoma.  相似文献   

Mast cell numbers in normal and glaucomatous canine eyes   总被引：1，自引：0，他引：1  

C Louden  J A Render  W W Carlton 《American journal of veterinary research》1990,51(5):818-819

Numbers of mast cells in the cornea, sclera, choroid, ciliary body, iris, and retina of sections of globes from 35 clinically normal dogs and 34 dogs with secondary glaucoma was determined. Fixed globes were trimmed along a vertical midsagittal plane and embedded in paraffin. Tissue sections, approximately 6 microns thick, were stained with toluidine blue for identification of mast cells. In normal globes, most of the mast cells were observed in the anterior portion of the uvea, and fewer mast cells were seen in the choroid and sclera. Mast cells were not observed in the retina and were seldom observed in the cornea of dogs with or without glaucoma. In sections of glaucomatous globes, mast cells were distributed evenly in the uvea and sclera, and fewer mast cells were present than in normal globes, regardless of the cause of glaucoma.  相似文献   

Growth and yield response of ‘Correll’ peach trees to fumigation with DBCP     

H.C. Williams  W.A. Dozier Jr.  C.E. Evans  C.C. Carlton  K.C. Short 《Scientia Horticulturae》1983,20(4):349-354

A study was conducted to evaluate the effect of the nematicidal soil-fumigant DBCP (1,2-dibromo-3-chloropropane) on a peach (Prunus persica L. Batsch.) orchard planted on a site with high potential for “short life”. ‘Correll’ peach trees on ‘Lovell’ rootstock were planted on a Ruston fine sandy loam soil (Typic Paleudult, fine loamy, siliceous, thermic) on which 2 generations of peach trees had been grown. Increased tree growth and yield occurred when DBCP was applied twice (pre-plant and 1 year post-planting). After 4 years, there were no differences in the nematode populations or foliar nutrient content as a result of fumigation with DBCP.  相似文献