The isolation and nature of campylobacters (microaerophilic vibrios) from laboratory and wild rodents.

Faeces voided by eight species of laboratory or feral rodents were cultured for campylobacters by means of selective methods. Campylobacters were isolated from bank voles and from rats, but not from rabbits, laboratory mice, hamsters, guinea-pigs, field mice or field voles. In routine biochemical tests isolates from bank voles resembled a type of Campylobacter fetus that causes infectious infertility in cattle; isolates from rats resembled Campylobacter coli associated with swine dysentery. Electrophoretograms of acid plus phenol soluble proteins revealed striking differences between isolates from rodents, C. fetus and C coli. It is concluded that campylobacters are more widespread in rodents than hitherto realised, and that routine methods for differentiating campylobacters do not allow an adequate correlation with pathogenicity or habitat.

The effect of the nitroimidazole drug dimetridazole on microaerophilic campylobacters.

Dimetridazole, a nitroimidazole drug reported to act only on obligately anaerobic micro-organisms, is widely used for the prevention and treatment of swine dysentery. Forty-four strains of the microaerophilic bacterium Campylobacter coli isolated from either healthy or diseased pigs, and a strain of Campylobacter fetus, were all sensitive to dimetridazole. The sensitivities (minimal inhibitory concentration less than 10 microng per ml) were similar to those of anaerobic bacteria. Dimetridazole inhibited growth of campylobacters in a shaken culture in air, but did not inhibit uptake of oxygen. Inhibition of growth appeared to result from an inhibition of nucleic-acid synthesis and does not seem to depend upon interference with electron transport in the catabolism of pyruvate.

Enterocolitis in Hirschsprung's disease: a controlled study of the etiologic role of Clostridium difficile.

Cytopathic toxin neutralized by Clostridium sordellii antiserum was found in the feces of seven out of 13 children with Hirschsprung's disease complicated by enterocolitis (54%). Clostridium difficile was isolated from ten of these 13 children (77%). The frequency of fecal toxin positivity, the magnitude of toxin titers, and the isolation rate of C difficile were all significantly greater in children with Hirschsprung's enterocolitis than in children whose Hirschsprung's disease was not complicated by enterocolitis or in children without Hirschsprung's disease. It is suggested that C difficile may be causally related to enterocolitis in Hirschsprung's disease, but the age distribution of positive results indicates that the major etiologic role is confined to children under three years of age. Vancomycin was found to be an effective form of treatment in the children with enterocolitis in whom it was employed.

Swine dysentery: protection against experimental challenge following single dose parenteral immunisation with inactivated Treponema hyodysenteriae.

Groups of five pigs were vaccinated at three to four weeks old with either formolised Treponema hyodysenteriae in oil adjuvant alone, formolised T hyodysenteriae in oil adjuvant plus formolised Campylobacter coli in oil adjuvant, or sterile medium in oil adjuvant (as a control). Each group was challenged four weeks after vaccination by oral dosing on two consecutive occasions with pure cultures of the homologous strain of T hyodysenteriae plus direct contact with two pigs exhibiting severe swine dysentery. The disease was observed in two of five pigs immunised with T hyodysenteriae alone, three of five pigs immunised with T hyodysenteriae plus C coli and all five controls; haemorrhagic diarrhoea was exhibited only by the control group. Each pig immunised with T hyodysenteriae (alone or with C coli) recovered spontaneously, whereas four controls died. Vaccination with T hyodysenteriae also markedly reduced the severity and duration of clinical signs and of weight loss. No differences were observed in response to challenge between pigs immunised with T hyodysenteriae alone and pigs immunised with T hyodysenteriae plus C coli.

Observations on vaccine and post-infection immunity in contagious equine metritis.

The vaccination of four ponies on two occasions with a formolised culture of Haemophilus equigenitalis produced a high circulating antibody titre to the organism in each pony. Three out of four vaccinated and all of three unvaccinated ponies developed typical symptoms of contagious equine metritis (CEM) when subsequently challenged with a vaginal exudate containing H equigenitalis. Similarly, three ponies which had previously been infected with H equigenitalis and which had recovered spontaneously also developed contagious equine metritis when rechallenged with the organism. The clinical and bacteriological symptoms in the vaccinated ponies and in the rechallenged ponies were less severe than those observed in the unvaccinated ponies but H equigenitalis was still recovered 17 days after challenge from the three vaccinated ponies which had developed CEM. The vaccinated pony which remained free from infection did not exhibit the highest circulating antibody titre of the vaccinates before challenge.

Enterotoxaemia involving Clostridium perfringens iota toxin in a hysterectomy-derived rabbit colony.

During an explosive outbreak of fatal enteropathic disease involving Clostridium perfringens iota (i) toxin, a total of 183 deaths occurred in 18 weeks. The clinical signs and post-mortem findings are reported. Examinations for virus, Bacillus piliformis and coccidia were negative. Clostridium perfringens i toxin was detected in 22 of 27 animals examined (81.5%), but clostridia were not isolated. Various treatments were attempted. It is concluded that i toxin and the syndrome described are closely related.

A passive haemagglutination test for the detection of antibodies to the contagious equine metritis organism.

A passive haemagglutination test (PHT) which has been developed for the detection of antibodies to the contagious equine metritis organism (CEMO) in serum is described. Samples from each of 30 mares with metritis were positive with titres in the range 256 to 4096. Samples from each of 239 clinically normal mares and 30 colts and fillies believed not to have been exposed to CEMO were negative with titres of less than 256, the majority of samples (97 per cent) showing a titre of 32 or less.

Identification of the major antigens of Treponema hyodysenteriae and comparison with those of Treponema innocens.

Eleven strains of Treponema hyodysenteriae isolated from pigs with swine dysentery were examined by using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. T. hyodysenteriae strains formed a homogeneous group with respect to sodium dodecyl sulfate-soluble proteins. However, immunoblotting with antiserum from rabbits immunized with T. hyodysenteriae CN8368 revealed heterogeneity among the lipopolysaccharide complexes of different strains. Polypeptides of molecular weights between 30,000 and 36,000 were the predominant T. hyodysenteriae polypeptides detected by porcine immune serum. In contrast, Treponema innocens did not form a homogeneous group with respect to sodium dodecyl sulfate-soluble proteins. Adsorption studies and immunoblotting identified polypeptide antigens present on cells of T. hyodysenteriae which were not detected on cells of T. innocens. These unique antigens may play a role in the virulence of T. hyodysenteriae.

Active and passive immunization to protect against antibiotic associated caecitis in hamsters.

The administration of clindamycin to hamsters induces a lethal enterocolitis as a consequence of toxins produced in the alimentary tract by Clostridium difficile. The lethal and cytopathic effects of C. difficile toxins are neutralized in vitro by C. sordellii antitoxin and hamsters may be protected against clindamycin induction of caecitis by passive immunization using C. sordellii antitoxin. To examine active immunization using C. difficile and C. sordellii toxoids, groups of male and female Syrian hamsters were immunized on two occasions and challenged by parenteral clindamycin. A concentrated C. difficile toxoid protected 90% of females and 78% of males; the degree of protection per group decreased with dilution of the toxoid used for immunization. A similar degree of protection was observed in female hamsters immunized with a bivalent vaccine prepared from the partially purified toxins A and B of C. difficile. Immunization using a C. sordellii toxoid protected between 100 and 25% of females per group and between 50 and 12.5% of males per group.

Clostridial toxins in neonatal necrotising enterocolitis.

Clostridium difficile cytopathic toxin was found in the faeces or gut content of five of 39 neonates with necrotising enterocolitis (NEC). Toxin concentrations were uniformly low and did not differ from those found in healthy neonates. C difficile is unlikely to be involved in the pathogenesis of NEC. Stools from 33 babies with NEC were also tested for C perfringens alpha toxin, with negative results.