A comparison of two pre-enrichment media prior to immunomagnetic separation for the isolation of E. coli O157 from bovine faeces.

AIMS: To compare the sensitivity of two pre-enrichment broth media prior to immunomagnetic separation for the isolation of Escherichia coli O157 from cattle faeces. METHODS AND RESULTS: One-gram portions of 721 cattle faeces collected from 43 farms were pre-enriched in buffered peptone water containing vancomycin, cefixime and cefsulodin (BPW-VCC) and buffered peptone water without additives (BPW-WOA), respectively. A total of 137 samples were positive for E. coli O157: 127 pre-enriched with BPW-WOA and 89 pre-enriched in BPW-VCC. Representative isolates were tested for phage type, verotoxin and eae (E. coli attaching and effacing) gene sequences, resulting in the recognition of eight different types. All the E. coli O157 types recognized were isolated by both methods except for three different strains, each of which were isolated only on a single occasion: two by BPW-WOA and another by BPW-VCC. CONCLUSIONS: The results clearly demonstrate, under the conditions of this study, that BPW without antibiotics was the superior pre-enrichment medium for the isolation of E. coli O157 from cattle faeces. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of BPW-WOA in preference to BPW-VCC for the isolation of E. coli O157 from cattle faeces in future research and outbreak studies should lead to a higher number of positive isolates.

Factors influencing the shedding of verocytotoxin-producing Escherichia coli O157 by beef suckler cows.

A study was designed to investigate management factors that might influence the shedding of verocytotoxin-producing Escherichia coli (VTEC) O157 by beef cows in Scotland, where there is a particularly high rate of human infection. Thirty-two herds were visited at least monthly over approximately 1 year for collection of fresh faecal pat samples and information on management factors. The faecal pat samples were tested for VTEC O157 by established culture and immunomagnetic separation methods. Questionnaires were completed at the monthly visits to record management factors. Data were analysed using both univariate and multi-factor (GLMM) analysis. Changes in the number of cows in a group, dogs, wild geese, housing, and the feeding of draff (distillers' grains) were statistically significant as risk factors. The event of calving appeared to reduce the likelihood of shedding. Any effects of weaning or turnout were not statistically significant. It appears that the rate of shedding of VTEC O157 is influenced by several factors but possibly the most important of these are the circumstances of animals being housed, or, when outside, the presence of wild geese.

Causes of death of wild birds of the family Fringillidae in Britain.

The provision of supplementary food for wild birds in gardens during the winter months is common in the UK, but it is possible that it may precipitate infectious diseases in the birds. This paper describes the results of postmortem examinations of 116 wild finches carried out over a period of four years. The two commonest causes of death in areas where high mortality had been reported were infections with the bacteria Salmonella typhimurium DT40 and Escherichia coli O86. Coccidia of the genera Atoxoplasma or Isospora were found in several of the birds but were considered to be incidental. Megabacteria were also identified in some of the birds, for the first time in flocks of wild birds in the UK, but they were not considered to be significant.

Isolation of Escherichia coli O86:K61 producing cyto-lethal distending toxin from wild birds of the finch family.

Escherichia coli was recovered from selected tissues of 43 out of a total of 46 finches found dead in the Scottish Highlands during April-May of 1994 and 1995. The isolates did not ferment sorbitol, rhamnose, sucrose or melibiose; they belonged to serogroup O86:K61, produced cytolethal distending toxin (CLDT) and possessed the eae gene sequence. The consistent recovery of organisms producing CLDT and possessing the eae gene suggests that these organisms may have played a significant role in the finch mortalities.

Salmonella in sewage effluent and the relationship to animal and human disease in the north of Scotland.

During the period July 1982 to December 1984, the presence of salmonella organisms was investigated at weekly intervals in the sewage system and abattoir effluent of a town in the north of Scotland. Three hundred and fifteen isolations, representing 37 different serotypes, were made which included 20 different Salmonella typhimurium phage types and four different S enteritidis phage types. Ten of the serotypes were isolated from livestock in the district during the survey as well as in the periods immediately before and after the survey. There were seven recorded incidents of human infection, involving four salmonella serotypes, only three of which were isolated concurrently from sewage.

The association of non-clotting of cow's milk with scour in the single suckled beef calf.

An apparent correlation between the clotting ability of cows milk and the prevalence of scour in suckling calves was investigated. Fifty-eight per cent of the milk samples of mothers of scouring single suckled calves showed impaired clotting ability. While the cause of this remains unknown there appears to be a link with diet. The poor clotting ability is probably a contributory factor in the aetiology of scour in the suckler calf, as the abnormality has only been seen in the milk from mothers of scouring calves.

The possible involvement of seagulls (Larus sp) in the transmission of salmonella in dairy cattle.

A series of infections in a herd of dairy cows by different salmonella serotypes over a seven year period is described. The source of infection appeared to be the private water supply contaminated by seagulls.