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Sensitivity of 179 strains of thermophilic Campylobacter to 21 chemotherapeutic drugs was studied. Activity of the antibacterial agents against the pathogens was estimated by the MICs. The MIC50 and MIC90 were also determined. All the Campylobacter strains were sensitive to gentamicin, chloramphenicol, neomycin, furazolidone and furagin and resistant to cefazolin, polymyxin E, rifampicin, vancomycin and bacitracin. Differences in the attitude of the Campylobacter isolates from various sources and patients of various age groups to the chemotherapeutic drugs were detected. Possible consideration of the results of comparison of R spectra of Campylobacter strains and the levels of their resistance to antimicrobial drugs as epidemiological markers is discussed.

Two hundred Campylobacter jejuni and Campylobacter coli strains from the same number of adult Swedish patients with acute enterocolitis were tested regarding adherence to and invasiveness in HEp-2 cells and for enterotoxigenicity by the CHO-cell assay. The serogroup characteristics, heat-stable and heat-labile, for each strain were also investigated. Eighty-four percent of the strains were classified as C. jejuni and 16 percent as C. coli. All of the strains were adherent to HEp-2 cells, 39% were invasive and 31.5% enterotoxigenic. We found significantly more invasive strains in the non-enterotoxigenic group than in the enterotoxigenic one. There would seem to be no correlation between enterotoxigenicity or invasiveness and serogroup. The results of this study suggest the existence of multiple mechanisms for C. jejuni- and C. coli-induced diarrhoea and that the mechanisms may differ from one strain to another.

Campylobacter jejuni and C. coli strains were collected during three different years from adult patients with enterocolitis in Sweden (n = 372) from 49 patients in Kuwait, and Campylobacter strains from hens from Mexico, Pakistan and Sweden (n = 107) and Swedish pigs (n = 47). C. jejuni was the predominant species in human and hen isolates, and C. coli in pigs C. coli was significantly more common in human isolates from Sweden, and more common in hen isolates from Pakistan, than in hens from Sweden and Mexico. C. laridis was only isolated from pigs (17%) and was in no case enterotoxigenic. Both in human and hen isolates, C. jejuni strains were more enterotoxigenic than C. coli strains. C. jejuni strains from Swedish hens were less enterotoxigenic than those from Pakistan and Mexico (P less than 0.001), and strains from pigs were less enterotoxigenic than those from hens (P less than 0.001). We conclude that C. jejuni are more often enterotoxigenic and possibly more virulent than c. coli and C. laridis. The relative frequency of C. jejuni and C. coli in humans and animals differs from one country to another.

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.

Eleven-day-old chicken embryos were used to compare the relative virulence of minimally passaged human isolates of Campylobacter jejuni and Campylobacter coli. Graded doses of bacteria were inoculated onto the chorioallantoic membrane, and 50% lethal doses were calculated at 72 h postinfection. Strains varied markedly in their ability to invade the chorioallantoic membrane and kill the embryos. The 50% lethal doses varied by about 6 logs for 25 strains of C. jejuni, and by 2 logs for 5 strains of C. coli. Although both outbred and inbred embryos were employed in the study, the latter were found to be more susceptible to infection with most strains. All isolates were screened for plasmid DNA, but there was no apparent relationship between plasmid content and virulence of strains for the embryos. Neither could virulence be associated with the production of siderophores by the strains. The ability of selected strains of C. jejuni to invade the liver of embryos was also studied. The number of campylobacters culturable from the liver was found to be inversely related to the 50% lethal dose of the strain. By inoculating 11-day-old embryos intravenously, it was possible to demonstrate that a strain of C. jejuni which was poorly virulent after chorioallantoic inoculation was relatively noninvasive. Invasiveness alone, however, could not fully account for the lethality of two highly virulent strains of C. jejuni administered by the intravenous route. Finally, there was no correlation between motility and virulence in this model system.

Pregnant guinea pigs were used to compare the virulence of four human isolates of Campylobacter fetus ss. fetus and four of C. jejuni on the basis of their ability to cause abortion and bacteraemia. Of the four strains of C. fetus ss. fetus two produced abortion readily after intramuscular injection. The four C. jejuni isolates were, however, of comparatively low virulence and no differences between them were demonstrated. Some of the isolates differed in their ability to survive in vitro in human and guinea-pig serum. It is suggested that campylobacters vary in their virulence for man and that this may influence the outcome of infections. Guinea pigs may prove useful in studying the pathogenesis of systemic campylobacter infections.

Rectal swabs from dogs were examined for Campylobacter fetus ssp. jejuni. The rate of positive findings from dogs with diarrhoea was 17.2% compared with 11.1% from the group of control dogs (without diarrhoea). Thus dogs may, under Danish conditions, be reservoir for Campylobacter. Most of the isolations were made on bloodagar after filtration of the samples through 0.6 mu filters. The selectivity of two media developed for examination of human faecal samples was either too low or too high for the present purpose.

Adhesion of Campylobacter jejuni and C. coli to epithelial cells is thought to be a decisive step in enteritis. In this work, we tried to determine which bacterial components are responsible for this phenomenon. Outer membrane (OM) extracts were prepared from strains of C. jejuni (3 strains) and C. coli (2 strains). These strains had been isolated from stools of febrile patients with diarrhoea and were able to adhere to HeLa cells in culture. After incubation of bacterial OM extracts with HeLa cells in culture, bacterial adherent material was recovered, subjected to electrophoresis and immunoblotted. Bacterial adherent antigens were revealed by a rabbit antiserum raised against whole bacterial cells. Antigenic fractions, ranging from 26 to 30 kDa, were found to preferentially bind to HeLa cells (cell-binding fractions; CBF). These antigens were proteins and were distinct from flagellin and lipopolysaccharide. Bacteria incubated with a rabbit antiserum raised against homologous CBF, were unable to bind to HeLa cells. Moreover, the inhibitory effect decreased when the antiserum was diluted. Under the same conditions, a rabbit antiserum raised against a non-adherent OM fraction of 92 kDa did not prevent bacteria from binding to HeLa cells.

Enterotoxin production, a possible virulence factor, was determined in Campylobacter jejuni and Campylobacter coli by two different techniques, the CHO cell test and the GM1 enzyme-linked immunosorbent assay. The frequency of enterotoxigenic Campylobacter strains was 32% in strains from both humans with acute enteritis and healthy laying hens, as measured by the CHO cell test. The CHO cell test was significantly more sensitive than the GM1 enzyme-linked immunosorbent assay in the detection of enterotoxigenic strains. Enterotoxin production was compared with the presence of heat-stable and heat-labile antigens. There was no significant correlation between enterotoxin production and serogroups for C. jejuni or C. coli. The difference in enterotoxigenicity between C. jejuni (34.1%) and C. coli (21.9%) was not significant.

Observations were carried out on 22 Hereford bulls to determine the age at which they bacame carriers of C. fetus. During preliminary investigations, 5 bulbs were repeatedly exposed to the organism by artificial or natural means from the age of 18 months. All animals became longterm carriers on reaching an age of between 40 and 70 months. Prior to this, a temporary carrier state lasting from 4 to 29 days was produced in 4 bulls. In a subsequent experiment, 17 bulls of 3 different age groups were artificially exposed to C. fetus on 5 occasions over a 2-year period. Thirteen bulls became long-term carriers, including 9 (53%) when less than 4 years old. A transient carrier state occurred in 4 bulls, 2 of which subsequently became long-term carriers. It usually lasted 1-2 weeks, although in 1 animal the organism persisted for 11 weeks. These results are discussed in relation to the findings of other workers and it is concluded that the use of young bulls to limit the spread of C. fetus in infected herds is of dubious value.

Twenty-one isolates were tested for their ability to adhere to and invade HEp-2 cells in vitro. Of the 21 organisms tested, 2 did not invade the HEp-2 cells, and 1 of these did not adhere to the epithelial cells. Campylobacter jejuni clinical isolates were more invasive than the nonclinical strains that were tested. When HEp-2 cells were treated with cytochalasin B, the invasiveness of C. jejuni was reduced, indicating active participation of the host cell in the uptake of these organisms. The number of intracellular C. jejuni isolates decreased when Campylobacter whole-cell lysates were absorbed onto HEp-2 cell monolayers. Experiments were also conducted to identify the functional sites of the antigens responsible for expression of Campylobacter invasion. Oxidation of lysates with sodium meta-periodate significantly affected its inhibitory capacity. This implies that the Campylobacter invasive ligand appears to be dependent upon an intact carbohydrate moiety.

One hundred strains of Campylobacter jejuni/coli isolated from faeces of children with diarrhoea were characterised. Frequency of isolation of these microorganisms from faeces of children with enterocolitis symptoms was evaluated. In this group Campylobacter jejuni/coli constituted 11.4% of all isolates, being the dominant etiologic agent of these infections. Biotype pattern of 100 Campylobacter jejuni/coli strains was determined. Biotype I C.jejuni prevailed and C. coli constituted as much as 35% of all isolated strains. All isolated strains were characterised serologically according to typing scheme of Lior. Seventy four strains were typed and 22 were untypable, out of which four were rough. Two new serotypes were isolated: LIO 71 and LIO 72, LIO 4 and LIO 72 serotypes were the most frequently isolated. Frequency of isolation of Campylobacter jejuni/coli strains were also determined in the period from january 1985 to august 1987.

Two cases of infection with Campylobacter fetus subspecies intestinalis are reported. In a 46-year-old farmer the development of septicaemic campylobacteriosis with acute gastroenterocolitis was favoured by malnutrition due to chronic alcoholism. After treatment with erythromycin the patient recovered completely. The second patient, a 40-year-old worker with meningitis, recovered after combined streptomycin-erytro-mycin therapy. In both patients antibodies against homologous and reference strains of Campylobycter fetus subspecies intestinalis, serotype 1 (Mitscherlich) were demonstrated in titres ranging from 1:16 to 1:64 by type the complement-fixation test.

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.

Fourteen isolates of Campylobacter jejuni of different serotypes and one Campylobacter coli isolate, from various human and animal sources, were tested for potential pathogenic mechanisms. Enterotoxin production was not detected in the infant mouse test or by calf and piglet ligated intestinal loop studies. Isolates were not invasive by the Sereny test. All isolates associated with and penetrated HeLa cells, although both actions occurred generally in a minor way under the conditions of our study. The C. coli isolate showed extensive HeLa cell association, but three other C. coli isolated tested did not. None of the 15 isolates produced diarrhea or death in 3-day-old chickens inoculated orally and observed for 3 days, nor did they consistently produce diarrhea and death in 9- to 10-day-old infant mice over a 3-day period after oral inoculation. Diarrheal disease and mortality were not observed when 3-day-old gnotobiotic chickens were infected with one of five isolates and observed over a 2-week period.

Campylobacter fetus ss. jejuni has recently been recognized as a frequent enteric pathogen of man. Although long known as a significant pathogen of domestic animals, little is known regarding mechanisms of colonization and pathogenesis. In an effort to study the colonization and morphology of this organism, we used scanning electron microscopy to examine ilea and colons from mice in which a human isolate of C. fetus ss. jejuni had been inoculated. When inoculated into the ileum of the mice, a transient colonization was observed by 24 hours and had disappeared by 48 hours. Colonization of the colon first appeared at 48 hours and persisted at least three weeks. When inoculated directly into the colon, colonization appeared within 24 hours in the colon and persisted at least 16 days. Severe colonic necrosis and mucosal degeneration were observed in colons only in those mice which were inoculated via the colon. In the infected colons, the C. fetus ss. jejuni organisms were enmeshed in a fibrous network which may play a role in the attachment of bacteria to the mucosal surface. Differences between the morphology of C. fetus ss. jejuni in the mouse model and that found in pure culture were observed and may represent distinct tissue and culture phases of growth.

Two groups of Syrian hamsters received 3 weeks apart from a commercial supplier became ill and were found to have proliferative ileitis (transmissible ileal hyperplasia). Seventy-five of 200 hamsters from one group and 60 of 200 from another group were evaluated by bacteriological and histopathological techniques. Campylobacter fetus subspecies jejuni was isolated from all hamsters showing clinical signs of proliferative ileitis. The organism was recovered from fecal swabs and the ileum. Many asymptomatic animals had microscopic lesions characteristic of proliferative ileitis, and all except one were culture positive for C fetus subspecies jejuni. A group of 48 hamsters from another commercial source and free of the disease were culture negative for C fetus subspecies jejuni. These animals were inoculated by gavage with one of the following: extract of affected ileum (eight hamsters), 1 X 10(8) viable C fetus subspecies jejuni organisms (28 hamsters), or sterile saline (12 hamsters). Ileal-extract inoculated hamsters were culture positive and five of eight developed clinical signs of ileal hyperplasia. Pure-culture-inoculated hamsters had colonization of the ileum by C fetus subspecies jejuni but did not develop hyperplasia of the ileum. With this data and the tendency of C fetus subspecies jejuni to be associated with clinical enteric disease in a variety of animals and man, we suggest that C fetus subspecies jejuni may have an etiologic role in proliferative ileitis of hamsters. Other synergisms or predisposing factors also may be involved.

An investigation was carried out into the occurrence of Campylobacter fetus subsp. jejuni on the surfaces of fresh and chilled pig carcasses. Swabs were taken of the water in the scald-tank, from cut surfaces, and from cut surfaces of carcasses that had been stored at 5 degrees C for 4 days. A total of 310 swabs was investigated, of which 10 were from the scald-tank, 100 from livers, 100 from cut surfaces, and 100 from cut surfaces of carcasses stored at refrigeration temperature. A specific enrichment process was employed for isolation of the bacteria. Campylobacter fetus subsp. jejuni was isolated from 43% of the liver swabs, from 56% of those from the cut surfaces, and from 32% of swabs from the cut surfaces of carcasses stored at refrigeration temperature. Campylobacter bacteria were not, however, isolated from the scald-tank. The high level of contamination found in this investigation is considered to create a possible source of Campylobacter infection for animal and Man.