Consequences on emergence of resistant bacteria from the use of antibacterials in animal husbandry.

Concern over the appearance of resistant bacteria in domestic animals and birds led in Great Britain to the establishment of a Government Committee of Enquiry on the use of antibiotics in Animal Husbandry and Veterinary Medicine known as the Swan Committee. This Committee made a number of recommendations about surveillance and control of diseases of animals communicable to man which included the establishment of a system of data collection. These recommendations were incorporated in a legal statute, the Zoonoses Order of 1975. Data on the incidence of salmonellosis and of antibiotic resistance in Great Britain are presented in this paper together with a consideration of the epidemiology of salmonellosis and its control.

Serological comparison of the Escherichia coli prototype strains for the F(Y) and Att 25 adhesions implicated in neonatal diarrhoea in calves.

Slide agglutination tests using single absorbed and double absorbed antisera indicated that the Att 25 prototype Escherichia coli strain 25 KH9 produces the F(Y) adhesion; that this E coli also produces at least one other surface antigen not found on the F(Y) prototype E coli strain 11a; and that F(Y)+ E coli strain 28a produces at least one other surface antigen not produced by the prototype strains for the F(Y) and Att 25 antigens. These antigens were found on E coli isolated from outbreaks of calf diarrhoea in the United Kingdom.

The serological responses of calves to live Salmonella dublin vaccine--a comparison of different serological tests.

The serological responses to live Salmonella dublin vaccine was assessed in three groups of calves; three-day-old colostrum-deprived (3DO C-), three-day-old colostrum-fed (3DO C+) and three-month-old (3MO), by the following tests; serum agglutination test (SAT), indirect haemagglutination test (IHA), complement-fixation test (CFT) and antiglobulin test (AGT). Serological activity was detected by all the tests in the 3MO calves. In the 3DO C+ calves no serological activity was detected by either the somatic SAT or IHA but low levels of CF and somatic AGT antibodies were produced. In 3DO C- calves serological activity, often at low levels, was detected by all the tests except the somatic SAT. High levels of flagellar agglutinins were detected in both groups of 3DO calves. It was concluded that with the exception of the flagellar SAT the tests were affected by the age of the calf and in 3DO calves also by the presence of colostral antibodies. However, the use of the SAT in 3MO calves would provide an indication as to the potency of salmonella vaccines.

The production of F41 fimbriae by piglet strains of enterotoxigenic Escherichia coli that lack K88, K99 and 987P fimbriae.

The enterotoxigenic Escherichia coli strains 1676, 1706, 1751 and KEC96a, which do not produce fimbrial adhesive antigens of the K88, K99 or 987P antigen type reacted both in vitro and in vivo with antiserum to F41 fimbriae in an indirect immunofluorescent antibody technique. Antiserum used to demonstrate material B, an adhesive antigen thought to mediate the adhesive and mannose-resistant (MR) haemagglutinating properties of E. coli strains 1676, 1706 and 1751, reacted in vitro with an F41+ strain. The antiserum also inhibited the MR haemagglutinating activity of F41 antigen and gave an anionic precipitation line in immunoelectrophoresis experiments with an extract containing F41 antigen. The MR haemagglutinating properties of an antigen extract containing material B from E. coli strain 1706 was neutralized by antiserum to F41 fimbriae and by OK antisera to E. coli strains that produce both F41 and K99 fimbriae. These sera also gave an anionic precipitation line with the MR haemagglutinin from E. coli strain 1706 and the MR haemagglutinin gave a line of identity with F41 in gel diffusion experiments with antiserum to F41 fimbriae. OK antisera to K99+ F41- bacteria and OK antisera to K88+ bacteria and 987P+ bacteria did not react with this haemagglutinin. Transmission electron microscopy on the ileum of newborn gnotobiotic piglets infected with E. coli strain 1706 showed irregular, poorly defined filamentous material surrounding some,though not all, bacteria but regular fimbrial structures were not visible.(ABSTRACT TRUNCATED AT 250 WORDS)

An examination of Escherichia coli strains isolated from cases of bovine mastitis for possible virulence determinants.

Ninety-five strains of Escherichia coli isolated from cases of bovine mastitis were examined for the possession of some of the possible virulence determinants. Ten strains which caused haemagglutination of bovine and ovine erythrocytes were considered to be fimbriated and an additional strain caused agglutination of chicken erythrocytes. Colicines were produced by fifteen strains and in three strains the colicine was identified as Col V. Forty-one of 71 strains that were examined serologically possessed capsular or envelope K antigens.

Use of "E. coli" K99 vaccines in ewes to passively protect lambs against experimental colibacillosis.

Pregnant ewes were vaccinated with partially purified, cell free K99 antigen prepared from the enterotoxigenic E. coli (ETEC) strain (0101:K99:NM) to passively immunize their lambs via the colostrum. After sucking their dams the lambs were infected orally with 10(10) - 10(11) organisms of the heterologous ETEC strain B44 (09:K30:K99), which possesses only the K99 antigen in common, within 4-21 h. of birth. All four control lambs from unvaccinated ewes challenged with E. coli strain B44 developed severe watery diarrhoea whereas none of the 10 lambs from vaccinated dams showed any signs of illness. Vaccination stimulated the production of K99 antibodies which could be detected by an indirect haemagglutination test and haemagglutination inhibition test. Experiments with brush border cells from calf intestine showed that the antibodies were associated with anti-adhesive activity. The antibodies which were predominantly IgG did not neutralize the activity of heat stable enterotoxin and it was concluded that neutralization of the adhesive properties of K99 positive E. coli by colostral antibodies significantly contributed to the resistance of the lambs from vaccinated dams.

Immunization of animals with gal E mutants of "Salmonella typhimurium".

A galactose epimeraseless (gal E) mutant of Salmonella typhimurium was investigated in mice, calves and poultry for its suitability as a live vaccine. In mice a very highly significant difference in the mortality rates was observed when vaccinated and non-vaccinated animals were challenged with virulent strains of S. typhimurium and S. dublin. In calves, doses of 10(6) and above of gal E mutant injected subcutaneously provided highly significant protection in terms of mortality and prevalence of symptoms when challenged orally with S. typhimurium. Renal lesions were found in a number of calves and studies were undertaken to investigate their pathogenesis. The results of these studies suggested that gal E. mutants were unlikely to produce the renal lesions. When day-old chicks were vaccinated orally with live gal E mutant of S. typhimurium and challenged orally 14 days later there was a statistically significant reduction in faecal shedding, in the salmonella carrier status at slaughter and in the numbers of salmonellae in the broiler house environment. The vaccine however, had a significant effect on the live weight gain of the birds.

Adhesive properties associated with the Vir plasmid: a transmissible pathogenic characteristic associated with strains of invasive Escherichia coli.

Escherichia coli strain S5 (O15:K+:H21) isolated from a septicaemic lamb and previously shown to possess a virulence plasmid, Vir, attached in vitro to calf epithelial tissue from the ileum, oesophagus and trachea in the presence of 0.5% (w/v) D-mannose. The Vir+ recombinant strains 711v and H209av, which had received the Vir plasmid(s) from strain S5, also attached to these epithelia but the parent strains 711 and H209a without the Vir plasmid were non-adhesive. The attachment of the Vir+ strain 711v to intestinal brush borders was inhibited by antiserum to live Vir+ strain H209av but not by antiserum to strain H209a lacking Vir. No adherence occurred with Vir+ organisms grown at 18 degrees C or after heating at 65 degrees C. Adhesion was unaffected by 0.5% (w/v) formaldehyde. Glucosamine, mannosamine, their N-acetyl derivatives and wheat germ lectin each inhibited attachment of Vir+ strain 711v to brush border epithelia.

Adhesion in vitro and in vivo associated with an adhesive antigen (F41) produced by a K99 mutant of the reference strain Escherichia coli B41.

A K99-negative mutant of the K99 reference strain Escherichia coli B41 (O101:K99) was isolated (strain B41M). It did not react with OK antiserum to a K12 K99+ recombinant or with OK antiserum to K99-positive organisms from the O8, O20, or O64 serogroups, but it did react with OK antiserum to K99-positive organisms from the O101 and O9 serogroups. The mutant hemagglutinated sheep erythrocytes and attached in vitro to calf enterocytes when cultured at 37 degrees C but not when grown at 18 degrees C. Attachment was mannose resistant but susceptible to heating and formaldehyde. These properties were associated with the presence of fimbriae. The isolated hemagglutinin migrated to the anode in immunoelectrophoresis experiments, competitively inhibited attachment of strain B41M to calf enterocytes, and could be demonstrated adhering to these cells in vitro by indirect immunofluorescent staining. The anionic hemagglutinin is referred to provisionally as F41. Germfree piglets infected with strain B41M developed diarrhea within 16 h. Scanning electron microscopy showed groups of bacteria adherent to the microvilli of villous enterocytes. Indirect immunofluorescent staining demonstrated the presence of F41 antigen in vivo.

Salmonella dublin infection of calves: use of small doses to simulate natural infection on the farm.

Small numbers of Salmonella dublin were used to infect calves in an attempt to simulate natural infection on the farm. Twenty calves were exposed to S. dublin by one or more of the following methods: Sucking cows which were excreting S. dublin in their faeces (less than 10(2)-10(5) organisms/g). Housing on S. dublin contaminated bedding. Drinking S. dublin contaminated water (10(2)-10(4) organisms/ml). During this experiment some calves were given therapeutic does of oxytetracycline. After exposure the calves were examined for faecal excretion of S. dublin (in some instances mouth swabs and blood samples were also examined) and for clinical signs of illness. Most of the calves became infected with S. dublin but excretion was usually sporadic and the numbers of salmonellas excreted were small. No clinical signs of salmonellosis were observed by S. dublin was isolated from one calf at post-mortem. Another six calves, dosed orally with either 10(6) or 10(8) S. dublin, showed signs of mild illness and although three calves had diarrhoea excretion of salmonellas was intermittent. S. dublin was isolated from one of these calves at post-mortem.

Salmonella infection in horses in England and Wales, 1973 to 1979.

During the period 1973 to 1979 the number of recorded incidents of equine salmonellosis increased from 23 in 1973 to a peak of 111 incidents in 1976, but has since decreased to 32 in 1979. Of the 416 incidents recorded during the period of the survey 292 were caused by Salmonella typhimurium and 121 by 33 different serotypes; in three instances rough strains of salmonella were involved. The number of incidents caused by serotypes other than S typhimurium increased from one in 1973 to 32 in 1976. The number of different salmonella serotypes increased from two in 1973 to 23 in 1977 and has subsequently declined. Drug resistance monitoring of salmonella strains from horses showed that most of the strains were resistant to streptomycin and sulphonamides, although resistance to other antibacterial drugs used was low. Seventeen different patterns of antibiotic resistance were observed but resistance to more than two antibiotics was uncommon.