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Biomedical subjects

C Wray

Publications and source records attributed to C Wray.

At least 91 records · Page 5Linked to original sources
PubMed1988

Vero cytotoxin production and presence of VT genes in Escherichia coli strains of animal origin.

Vero cytotoxin (VT) production has been studied in 34 Escherichia coli strains isolated from animals with enteric diseases. The strains were tested by DNA hybridization with probes for VT1 and VT2 sequences and also in toxin neutralization experiments with specific antisera. Twenty bovine strains, belonging to nine different O serogroups, produced VT1 or VT2 but not both toxins. In contrast, all 14 porcine strains of four different O serogroups produced VT2 only. Six of these porcine strains, belonging to serogroups O138, O139 and O141, were isolated from cases of oedema disease. In general, the porcine isolates produced toxin at a lower level than the bovine strains.

Animals↗
PubMed1987

Differentiation of Salmonella typhimurium DT204c by plasmid profile and biotyping.

Seventy per cent of the United Kingdom isolates of Salmonella typhimurium from calves are phage type 204c and the study of the epidemiology of this organism requires additional methods of strain characterisation. This paper describes the applications of biotyping and plasmid-profile analysis for this purpose. One hundred and eleven isolates from 73 outbreaks of disease were examined. All belonged to the same primary biotype, although strains from 39 of the outbreaks differed in secondary tests in failing to ferment m-inositol at 25 degrees C. Four different antibiotic resistance patterns were detected among the isolates, which possessed seven distinct plasmid profiles. The spread of a distinct type through the calf marketing chain was investigated by using these techniques.

Animals↗
PubMed1987

Epidemiology of Salmonella typhimurium infection in calves: excretion of S typhimurium in the faeces of calves in different management systems.

Twenty-five batches of market-purchased calves, comprising 589 animals on 11 farms, were examined for the excretion of salmonellas for at least 28 days after their arrival. Salmonellas were found in 217 (51 per cent) of 423 calves from 18 of 21 batches on nine farms. The calves were housed in single pens on eight farms and in groups on the others. The trends in new excreters and the proportion of Salmonella typhimurium excreters were similar in both types of housing, a peak of excretion which was slightly higher in single penned calves, being reached 18 to 19 days after arrival. New excreters were found at most samplings in both types of housing, but the peak of new excreters appeared earlier and declined sooner in single penned calves. On average, single penned animals excreted salmonellas longer. Salmonella dublin was found only in single-penned calves, and the trend in excretion was similar to that for S typhimurium in single-penned calves except that the peak was at about 28 days. Prophylactic feeding of antibiotics was practised on nine farms, but appeared to have no influence on the excretion of salmonellas. Salmonellas were isolated from the environment in six of nine farms studied, even after cleaning and disinfection. It is suggested that the persistence of salmonellas in the environment deserves more attention in the formulation of control programmes.

Animals↗
PubMed1987

A note on the effect of the lactoperoxidase systems on salmonellas in vitro and in vivo.

The lactoperoxidase system (LPS), a natural bactericidal system in milk, was investigated for its activity against salmonellas in vivo and in vitro. In acidified raw milk, in which the LPS was supplemented with an exogenous supply of H2O2, the numbers of salmonellas decreased rapidly. Different salmonella serotypes were affected to the same extent; rough strains, however, were more susceptible than smooth strains. When calves were fed on fresh milk, containing the LPS, and challenged with Salmonella typhimurium in doses of either 10(9) or 10(10), the clinical findings and salmonella excretion patterns were similar to those of control calves fed on heated milk. It was concluded that further studies, perhaps in the field, are necessary to evaluate LPS as a possible non-antibiotic system to control salmonellosis.

Animals↗
PubMed1987

Effect of bovine virus diarrhoea-mucosal disease virus infection on salmonella infection in calves.

The possibility that bovine virus diarrhoea virus (BVDV) infection could aggravate concurrent salmonella infections was investigated in two series of experiments with Salmonella dublin and S typhimurium. In both series of experiments the clinical signs tended to be more severe in dual infections than in those with salmonella alone. Faecal excretion of S dublin was similar in both single and dual infected calves. A protracted bacteraemia occurred only in two dual infected calves, one of which died from suppurative meningitis. In the case of S typhimurium, body temperatures, passage of abnormal faeces and isolation rates of salmonella from faeces were significantly increased. The results suggest that BVDV infection may indeed exacerbate the effects of salmonella infection and the aetiological relationship of the two agents should be considered during outbreaks of bovine salmonellosis.

Animals↗
PubMed1986

Apramycin and gentamicin resistance in Escherichia coli and salmonellas isolated from farm animals.

Since the aminoglycoside antibiotic apramycin was licensed for veterinary use in 1980, all isolates of Escherichia coli and salmonellas received at the Central Veterinary Laboratory have been monitored for resistance to apramycin and the related antibiotic gentamicin. During the period 1982-4, the incidence of resistance in E. coli to apramycin increased from 0.6% in 1982 to 2.6% in 1984. In salmonellas the incidence of resistance to apramycin increased from 0.1% in 1982 to 1.4% in 1984. Resistance to both apramycin and gentamicin was detected in six different salmonella serotypes, although an isolate of Salmonella thompson from poultry was resistant to gentamicin but not apramycin. Most of the cultures were isolated from pigs, although the incidence of apramycin resistance in S. typhimurium (DT 204C) from calves has shown a recent dramatic increase. All the isolates with one exception produced the enzyme aminoglycoside 3-N-acetyltransferase IV (ACC(3)IV). The resistance was transferable by conjugation in most of the strains examined, and the plasmids specifying the resistance have been found to belong to a number of different incompatibility groups. Plasmids from three E. coli strains were compatible with all the reference plasmids and belonged to a previously undescribed group which was investigated further. It is suggested that bacteria from humans should be examined for resistance to apramycin and gentamicin to determine the possibility of the antibiotic-resistance bacteria, and their genes, spreading from animals to humans.

Acetyltransferases↗
PubMed1986

Salmonellosis in two dairy herds associated with a sewage farm and water reclamation plant.

Two dairy herds, situated on a sewage farm, were monitored for the presence of salmonellas following outbreaks of Salmonella dublin infection. In addition an S. dublin control scheme, which involved examination of adult animals and calf vaccination, was instigated. During the period 1975-84, 12 salmonella serotypes and 10 phage types of S. typhimurium were isolated from the cattle and their environment although their presence was seldom associated with disease. Two adult S. dublin excreters were detected but it was concluded that none of the tests employed to examine the adult animals was sensitive enough. The prevalence of disease in the calves was low and although vaccination may have been beneficial it did not eradicate S. dublin infection. Thus S. dublin persisted in adults and calves during the 8-year period but its presence was seldom associated with disease. The results are discussed with regards the disease risk to animals from the agricultural use of sewage sludge and the public health aspects.

Animals↗
PubMed1986

Some aspects of the occurrence of resistant bacteria in the normal animal flora.

The paper outlines some of the problems encountered in assessing the occurrence of antibiotic resistance in the normal flora of animals, using Escherichia coli as an example. Additional information is provided on the occurrence and mechanisms of resistance in Clostridium perfringens, Pasteurella haemolytica and Staphylococcus aureus, and some of the factors which may affect this resistance. The paper concludes with general considerations about the choice of organism, the sample size and the desirability of designing standard protocols.

Animals↗
PubMed1986

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.

Animal Husbandry↗
PubMed1985

Is salmonellosis still a serious problem in veterinary practice?

Salmonella infections of food animals are of concern to both the food industry and to the public health authorities. Salmonellosis is one of the major zoonotic diseases and its impact on veterinary practice may be judged by a number of criteria. Some of these are examined to determine the extent of the problem.

Animals↗
PubMed1984

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.

Agglutination Tests↗