Evaluation of Disinfectants against E. Coli (VTEC O157) and Campylobacter in Vitro and on Farms

<p>Escherichia coli are common Gram-negative bacteria that form a normal part of the gut flora of humans and animals. However, among the different pathotypes of E. coli some can cause human disease, with the verocytotoxigenic E. coli (VTEC) serotype O157:H7 being one of the most virulent and widespread causing haemorrhagic colitis and haemolytic uraemic syndrome. In 2009, an outbreak of VTEC O157:H7 led to severe illness in a number of visitors to an open farm in Surrey with several cases of life-threatening haemolytic uraemic syndrome in young children. VTEC O157 can be found in several livestock species without causing clinical symptoms in these animals, and the main reservoir seems to be cattle, in particular youngstock.
Campylobacteriosis is the most common cause of acute bacterial enteritis in the UK with the main food borne source being poultry meat.</p>

<p>In order to prevent carry-over of pathogens from one group of animals to the next and from animals to people, disinfectants are applied to surfaces in animal accommodation. A wide range of products belonging to several groups of chemicals are licensed and used for this purpose, but not all disinfectants are equally effective. While the presence of organic matter does affect the efficacy of all disinfectants to some degree, some are more effective than others in the presence of organic matter due to their chemical properties.</p>

<p>In addition to disinfection of surfaces, boot dips are in use on many farms to prevent carry-over of pathogens between different groups of animals. However, disinfectants in boot dips need to be particularly effective in the presence of faecal matter, and previous studies have found that boot dips as currently used in many livestock enterprises are often not efficient barriers to infection and may therefore represent a waste of resources leading to a false sense of security.</p>

<p>On many farms, hand sanitizers are used where hand washing facilities are not feasible to reduce the bacterial count on hands and gloves. The use of hand sanitizers has been recommended as a key element of biosecurity, but little hard data exists on efficacy against VTEC O157 or Campylobacter. The proposed work will provide robust data on the best performing disinfectants to be used against VTEC O157 and Campylobacter on livestock premises and will give guidance on which products are most suitable for the different types of applications. These results will be of high practical value and will be used in the future to better inform farmers about the most suitable products they should use to control those bacteria.</p>

<p>Several studies suggest that exposure of VTEC O157:H7 to biocides may to lead to an adaptive response which is also likely to lead to cross-resistance to other antimicrobials and biocides. However, the adaptive response mounted is likely to be dependent on the biocide used, its concentration, the number of times and duration of each exposure. The aim of the molecular component of this project is to assess these factors critically at the molecular level using global gene expression studies to understand the basis of development of biocide resistance in VTEC O157 strains and determine conditions which are least likely to lead to such resistances in future, so an effective method may be recommended for long term use on farms as a result of this study.</p>

<p>In addition to the expected scientific results, the proposed work on VTEC O157 will help maintain expertise on working with this pathogen in category 3 facilities at AHVLA Weybridge and also allow for training of two members of staff to work on VTEC O157 to allow continuity of this work at the Weybridge site following the upcoming retirement of currently trained staff. The proposed Campylobacter work will contribute to the maintenance of expertise on Campylobacter at the AHVLA and the development of laboratory methods.</p>

<p>The results from the project will be summarised in scientific publications but can also be produced as an information leaflet for farmers.</p>