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Biomedical subjects

C Wray

Publications and source records attributed to C Wray.

At least 19 recordsLinked to original sources
PubMed1998

Studies of the presence of verocytotoxic Escherichia coli O157 in bovine faeces submitted for diagnostic purposes in England and Wales and on beef carcases in abattoirs in the United Kingdom.

A survey of beef carcases in abattoirs in the UK was carried out in order to estimate the prevalence of contamination with verocytotoxin-producing Escherichia coli (VTEC) serogroup O157. Contamination with verocytotoxin-producing E. coli (VTEC) O157 was confirmed in 0.47% of the 4067 (95% confidence limits 0.22-1.00%) of neck muscle samples. A significant tendency for carcases present in the same abattoir on the same day to have similar results was found, thus suggesting cross contamination. VTEC O157 was found in 0.83% of 6495 bovine faeces samples routinely submitted for diagnostic purposes to Veterinary Investigation Centres in England and Wales. Of the samples from cattle less than 6 months old, 3.7% of 68 samples from animals without gastrointestinal disease were positive for E. coli O157, in contrast to 0.75% of 2321 samples from cases of gastrointestinal disease. No association with season or herd type (beef or dairy) was found.

Abattoirs↗
PubMed1997

Studies on the development and use of a monoclonal sandwich ELISA for the detection of verotoxic Escherichia coli in animal faeces.

A sandwich ELISA using monoclonal antibodies to Escherichia coli verocytotoxins 1 and 2 for capture and detection was developed for detection of verocytotoxin-producing Escherichia coli (VTEC) in animal faeces. For optimal toxin detection, the faeces were cultured in MacConkey broth before subculture on to trypticase soy agar containing mitomycin C. It was possible to detect between 10 and 10(3) VTI-producing and 1 to 10 VT2-producing E coli/g faeces, and overall the sensitivity and specificity of the ELISA for VTEC in faeces were 80.5 per cent and 91.2 per cent, respectively, when compared with a verocell assay. A limited survey of faeces from healthy animals (89 cattle, 16 sheep, 22 pigs, 11 goats and six domestic fowl) and faeces from 144 cattle with enteric disease detected VTEC in 64 per cent, 63 per cent, 5 per cent, 45 per cent, none and 16 per cent of the samples, respectively.

Animals↗
PubMed1997

Distribution of Salmonella contamination in ten animal feedmills.

Detailed sampling of spillage and dust from milling equipment was carried out in nine animal feedmills, three of which were sampled twice. The salmonella isolation rate ranged from 1.1% to 41.7% of the samples and the most contaminated mills were those where the inside of the cooling systems for pellet or mash had been colonised by salmonella. A wide range of salmonella serotypes were isolated which included Salmonella typhimurium and S. enteritidis. Limited sampling every two weeks for an 18-month period in another animal feedmill showed marked variation in the contamination rate of samples and range of salmonella serotypes found. Contamination of ingredient intake pits and outloading gantries for finished products by wild bird droppings containing salmonella was also found in four mills.

Animal Feed↗
PubMed1997

Bacteriological and serological investigation of persistent Salmonella enteritidis infection in an integrated poultry organisation.

Bacteriological monitoring of broiler breeder farms, the hatchery, rendering plant and animal feed mill during 1991 identified a number of potential cross-contamination hazards, such as the use of processed poultry proteins in the company feed mill and contamination of egg trolleys and trays, which may have led to widespread dissemination of Salmonella enteritidis within an integrated poultry organisation. Serological monitoring of the flocks suggested that, in most cases, substantial exposure to S. enteritidis infection occurred during the mid-rearing stage whereas routine bacteriological monitoring of poultry house litter and dust samples, and meconium samples taken in the hatchery identified infection only after the onset of the laying period. At least 10 phage types and six plasmid profile types of S. enteritidis were identified in historic submissions from the organisation including one apparently specific plasmid profile type that was distributed throughout the various parts of the company. During sampling for this investigation, most of these strains were not identified, and the number of plasmid profile types was reduced to a single common UK type.

Animal Husbandry↗
PubMed1997

Use of antibody-coated cellulose sponges for enhanced isolation of salmonella.

One thousand, four hundred and fifty-one naturally contaminated samples from pig, poultry and cattle farms, poultry hatcheries and animal feed mills were examined in a trial in which transfer of small portions of cellulose sponge coated with salmonella somatic polyvalent antiserum was compared with transfer of standard liquid inocula from pre-enrichment to selective enrichment culture. Salmonella was found in 281 (19.4%) of the samples using the standard method, compared with 385 (26.5%) using the sponge method. It was therefore concluded that antibody-coated cellulose sponges could be a simple means of increasing the recovery of salmonellas from pre-enrichment broths and thereby enhancing the test sensitivity.

Animal Feed↗
PubMed1997

Immunomagnetic separation for enhanced flagellar antigen phase inversion in salmonella.

Immunomagnetic separation (IMS) was used to reduce delays in serotyping caused by slow flagellar phase inversion of diphasic salmonellas. Some 375 strains of 11 salmonella serotypes were examined using IMS. The mean time for successful flagellar phase inversion was reduced from 4.3 (range 1-18) d to 1.0 (range 1-3) d using the IMS method, and in a further experiment phase inversion was achieved within 8 h in 112 of a further 117 strains representing four salmonella serotypes.

Animals↗
PubMed1997

Attaching and effacing E. coli. Microscopic and ultrastructural observation of intestinal infections in pigs.

Pigs aged from neonate to 8 weeks with naturally occurring diarrhoea were submitted to a Veterinary Investigation Centre for routine diagnosis. They were retrospectively found to be infected with "attaching and effacing" E. coli (AEEC) on histological and ultrastructural examination of the intestinal tract. Subcultures of E. coli isolated from some of the affected pigs were tested against standard anti-sera and probed for the presence of verotoxin (VT) and "cae" genes. One strain of E. coli was positive for the VT gene and three VT-negative strains possessed the "cae" gene. This preliminary report suggests that in naturally occurring diarrhoea of suckling and weaned pigs, AEEC infection can be identified by histological examination of the intestinal mucosa and confirmed by electron microscopy, in the abscence of infection by recognised enteric pathogens on microbiological examination.

Adhesins, Bacterial↗
PubMed1996

Determination of an effective sampling regime to detect salmonella enteritidis in the environment of poultry units.

A study of the dissemination of Salmonella enteritidis in the poultry breeder industry in the UK showed that the choice of sites for sampling the environment of occupied houses and empty houses which had been disinfected after depopulation had a significant influence on the outcome. Increased isolation rates could be achieved by sampling nest box floors and dust in open slave feed hoppers in occupied poultry houses. Nest box floors were the most sensitive sites for detection of residual environmental contamination in poultry houses where enrofloxacin treatment had been used. Floor sweepings, nest box floors, slave feed hoppers, hydrated wall fabric junctions and high beams and pipes were the most sensitive sample sites in cleansed and disinfected poultry houses. The use of universal disinfectant neutralisers gave good results in laboratory trials but appeared to reduce the isolation rate from field samples.

Animals↗
PubMed1996

World Health Organisation--supervised interlaboratory comparison of ELISAs for the serological detection of Salmonella enterica serotype Enteritidis in chickens.

A collaborative exercise, supervised by the World Health Organisation, was set up to compare ELISAs used for the serological detection of Salmonella enteritica serotype Enteritidis in chickens. The aim was to ascertain how far agreement could be reached on the interpretation of optical density readings for high titre, intermediate titre and low titre sera. Two sets of sera were sent to 14 participants. The first set compared high, medium and low titre sera raised in specified-pathogen-free and commercial broiler breeder chickens. The second set comprised 20 sera of different antibody titres raised in commercial birds reared under laboratory conditions and sent blind. Both indirect and double-antibody sandwich blocking ELISAs were used with a number of different detecting antigens. With a few exceptions good agreement was reached on the interpretation of results obtained from high and low titre sera from the optical density obtained with a single serum dilution. Differences were observed in the interpretation of medium titre sera. The results suggested that most ELISAs produce reasonably comparable results and that practical problems may arise from interpretation of the results mainly as a result of the choice of the criteria used for differentiating sera obtained from infected and uninfected chickens. These problems are discussed.

Animals↗
PubMed1996

Persistence of Salmonella enteritidis in poultry units and poultry food.

1. Studies on the survival of Salmonella enteritidis in poultry units and food were carried out over a two-year period. 2. The organism persisted for at least one year in an empty trial house at the laboratory in which naturally-infected broiler breeder birds had previously been housed. A similar survival period was seen in a building which had housed an infected layer breeder flock, although infection was not detected in a subsequent pullet flock. 3. Salmonella enteritidis was also frequently found surviving outside poultry houses in small pockets of litter and fan dust which had been left after cleansing and disinfection of the site. On some poultry units S. enteritidis was also found in wild bird droppings. 4. Salmonella contamination appeared to persist preferentially in association with dust particles swept from the floor and in food troughs and S. enteritidis survived at least 26 months in artificially contaminated poultry food.

Animal Feed↗
PubMed1996

Seasonal variations in the isolation of Salmonella typhimurium, Salmonella enteritidis, Bacillus cereus and Clostridium perfringens from environmental samples.

Calf carcasses contaminated with S. typhimurium, B. cereus and Cl. Perfringens were placed in either a decomposition pit or in a deep burial pit. Salmonella was isolated from the soil around the decomposition pit for 27 weeks and for 15 weeks around the burial site. Salmonella re-appeared in soil samples during cold winter weather after an apparent 9-week absence from the decomposition pit and after 68 weeks in the burial site (a total of 88 weeks after the start of the experiment). There was also an annual rise in the isolation rate of B. cereus from the soil during the colder winter months, but Cl. perfringens appeared to be more prevalent in samples taken during spring of the second year of the study. A similar apparent rise in the prevalence of S. enteritidis during a cold winter period occurred in an empty poultry house that had previously held a naturally infected broiler-breeder flock.

Animals↗
PubMed1996

Development and evaluation of a simple, one-step salmonella isolation test.

A one-step test unit was developed which allowed migration of salmonellas to selective medium and indicated the presence of salmonella by motility inhibition using polyvalent flagella antiserum. Evaluation of the method using 1038 naturally contaminated samples led to identification of more contaminated samples than a standard method within 24 h as opposed to 96 h.

Animal Feed↗