The interaction of Clostridium perfringens and its toxins in the production of necrotic enteritis of chickens.

The intraduodenal administration of large numbers of Clostridium perfringens cells harvested from broth cultures and resuspended in PBS or fresh sterile thioglycollate broth produced a very mild form of necrotic enteritis. Administering an appropriate number of cells in culture supernatant, however, produced typical field-type disease. Alpha toxin was shown to be the significant toxin recoverable from broth-culture supernatant fluids.

The pathology of necrotic enteritis of chickens following infusion of crude toxins of Clostridium perfringens into the duodenum.

Necrotic enteritis was produced in 4-week-old chickens with bacteria-free crude toxins of Clostridium perfringens. Typical gross lesions could be seen as early as 3 hr after intraduodenal infusion of toxin was begun. Early microscopic lesions were observed at 20 minutes, progressing with time to involve most of the mucosa.

The pathology of necrotic enteritis of chickens following infusion of broth cultures of Clostridium perfringens into the duodenum.

Necrotic enteritis was consistently reproduced when enough active broth culture of Clostridium perfringens type A was infused intraduodenally. Typical lesions of necrotic enteritis were seen as early as 5 hr after infusion was begun. The histologic lesions observed at 1 hr were characterized by edema in the lamina propria and desquamation of epithelial cells.

Erysipelothrix rhusiopathiae infection in chukar partridge (Alectoris graeca).

Erysipelas was diagnosed in chukar partridges (Alectoris graeca) kept as hunting stock. Mortality was 265 of 500 (53%) over a period of one week.

Temperature sensitivity studies on selected strains on Mycoplasma gallisepticum.

Mycoplasma gallisepticum (MG324), a tylosin resistant strain of low virulence, was compared with four other strains with respect to their survival at temperatures from 46.1 to 48.9 degrees C.

Necrotic enteritis in broiler chickens. III. Reproduction of the disease.

Lesions typical of necrotic enteritis could be produced experimentally in from 11-26% of broiler chickens consuming feed containing approximately 10(7) Clostridium perfringens per gram. Highest mortality was produced using isolates from field cases of necrotic enteritis which were reisolated from experimental cases in the laboratory. Penicillin in the drinking water at 100,000 I.

The recovery of Mycoplasmas from the genital tracts of bulls in artificial breeding units in Ontarïo.

One hundred and thirty-two penial-preputial swabbings, 140 raw and 42 processed semen samples were cultured for mycoplasmas. Mycoplasma or acholeplasma were recovered from 87, 32 and one respectively, while ureaplasmas were recovered from 46, 34 and six respectively.

In vitro antimicrobial sensitivity of Mycoplasmas isolated from the bovine genital tract.

The in vitro antimicrobial sensitivity of 14 mycoplasma and 13 ureaplasma strains isolated from the genital tracts of bulls was examined. It was found that at relatively low concentrations, tetracycline, declomycin and tylosin were lethal to both types of organisms. Lincospectin, berenil, streptomycin and erythromycin were lethal to mycoplasmas but were only inhibitory to the ureaplasma strains at the same concentrations.

Studies on the control of Mycoplasma gallisepticum in hatching eggs.

Lincomycin-spectinomycin, while effective in eliminating Mycoplasma gallisepticum from hatching eggs when administered via the yolk sac, had a marked deleterious effect on hatch-ability when given by this route. On the other hand when lincomycin-spectinomycin was injected into the air cell there was a reduction in the level of experimental infection with an acceptable effect on hatchability.

Studies with radioactive endotoxin. I. Clearance of 51Cr-labelled endotoxin from the blood of calves.

The clearance of (51)Cr-labelled Pseudomonas endotoxin from the blood was studied in calves in a nontolerant and in an endotoxin-tolerant state. Calves were rendered tolerant to the toxic effects of the endotoxin by four daily intravenous injections of endotoxin at the dose rate of 5 microg/kg body weight. Clearance of a small amount of (51)Cr-endotoxin from the blood of nontolerant calves was almost complete within three minutes of injection and was not significantly faster in tolerant calves.

An infection in chickens with a strain of Mycoplasma gallisepticum of low virulence.

A slow-spreading infection due to a strain of Mycoplasma gallisepticum was detected serologically in a flock which remained free of clinical symptoms. The strain was shown to be tylosin resistant. Serological studies indicated that vertical transmission occurred.

Studies on the chick-lethal toxin of Eecherichia coli.

A toxin which is lethal for two week old chicks has been recovered from strains of Escherichia coli O78:K80 of bovine and avian origin and from avian isolates of serogroups O2, O45 and O109. The toxin is heat-labile, antigenic, high in protein, inactivated by pronase, trypsin, amylase, and pancreatic lipase. The toxin may be precipitated by ammonium sulfate or TCA treatment from the supernatant obtained by repeated centrifugation of sonicated cells.

Studies on the serological and immunological response of chickens to endotoxin and endotoxoid.

Chicks two, three and four weeks of age respond well serologically to endotoxin given intravenously, with the older chicks giving a better response. The induced immunity against live organism challenge produced by homologous endotoxin from Escherichia coli or Salmonella typhimurium is specific between these two organisms, however, cross-immunity occurs between E. coli 045 and E.

The transfer of endotoxin induced immunity from hens to poults.

Turkey hens were vaccinated six times with Salmonella typhimurium endotoxin prior to and during their egg production cycle. The resultant poults possessed a significant degree of immunity to challenge with S. typhimurium.

Endotoxin studies in chicks: effect of lead acetate.

Lead acetate administered intravenously in a mixture with endotoxin preparations potentiates the toxic effect of endotoxin for 14-21 day old meat strain chicks. A dose of 2.8 mg of lead acetate/100 g body weight is more effective with endotoxin than a dose of 2.