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Pathogenicity of 17 Campylobacter isolates for pregnant guinea pigs was investigated. Of 14 isolates, 12 (86%) produced rates of abortion ranging from 13% to 87%. Two isolates did not produce abortion. Reference strains of C fetus subsp venerealis produced abortion in 60% to 87% and C fetus subsp fetus produced abortion in 60% of the guinea pigs. Inoculated organisms were recovered from uterus, blood, liver, kidney, spleen, and gallbladder of the guinea pigs at rates as high as 83% for 2 ovine isolates and as low as 13% for 2 bovine and 1 human isolates. Most isolations were from the uterus. Two avian isolates were not recovered. Within the C jejuni and C coli group, the ovine and the human isolates appear to be more pathogenic. Swine, bovine, and avian isolates were less pathogenic. Seemingly, the pregnant guinea pig was a suitable and practical model for evaluating the pathogenicity of Campylobacter organisms, regardless of their host of origin.

Thirty-three, 10-week-old, specific-pathogen-free pigs were randomly allotted to 3 treatment groups: group 1--intragastrically given homogenized intestinal mucosa (crude inoculum) from pigs with naturally occurring proliferative enteritis; group 2--given cultures of Campylobacter sputorum subsp mucosalis; and group 3--controls. One pig from each group was killed 4, 7, 10, 14, 18, 21, 24, 28, 31, 36, and 38 days after inoculation. The earliest intestinal lesion observed in groups 1 and 2 was leukocytic exudate within crypt lumina and focal inflammation of the surrounding lamina propria. The lesions occurred primarily over ileal aggregated lymphoid nodules (Peyer's patches). These changes were followed by focal proliferation of immature crypt epithelial cells and infiltration of increasing numbers of macrophages into the lamina propria. Campylobacter sp-like organisms were observed within the cytoplasm of affected epithelial cells by light and electron microscopies. Lesions progressed to diffuse crypt cell proliferation, elongation of crypts, and loss of villi. Mucosal necrosis was not a prominent feature.

Fecal samples from 127 diarrheic and 3 healthy beef calves, representing 25 herds with enteric disease, were cultured for Campylobacter, using filtration and a selective medium. Campylobacter fetus subsp jejuni (CFJ) was isolated from 51 (40%) of the diarrheic calves representing 14 (56%) herds and from the 3 clinically healthy calves (1 each in 3 of these 14 herds). Campylobacter fetus subsp intestinalis was not isolated from the calves. Fecal samples from 36 diarrheic and 20 healthy lambs representing 8 ranches were negative for Campylobacter. Isolates of CFJ from aborted lambs and from the feces of calves, ducks, dogs, and persons, appeared identical from the standpoint of morphology and physiologic reactions. In 12 calves and 5 lambs fed cultures, CFJ became colonized. Three of the calves developed diarrhea, but 2 were compromised by other disorders at the time of challenge exposure. None of the other calves or lambs developed diarrhea, but 10 of the calves and all of the lambs had frank or occult blood in the feces. Lamb intestinal loops were not distended by cultures of CFJ, but some cultures caused pathologic changes in the loops. None of 10 cultures of CFJ tested caused diarrhea in infant mice. Campylobacter fetus subsp jejuni is apparently capable of causing irritation and pathologic changes in the intestinal tract of young calves and lambs. Additional studies are needed to assess the role of CFJ in spontaneous enteric disease of calves.

Strains of Campylobacter jejuni and C coli from human and animal sources were assessed for pathogenicity by their capability to produce abortions in pregnant guinea pigs. The pathogenicity rate varied from 7% to 87% for the C jejuni strains and from 0% to 53% for the C coli strains. Plasmid carriage was not found to correlate with pathogenicity as determined by ability of the strains to produce abortions in the pregnant guinea pig model.