Evaluating the New European Broth Microdilution Guidelines for Determining the Susceptibility of C. Jejuni and C. Coli

Campylobacter spp. remains the most common bacterial agent of gastroenteritis in humans. The overall trend of increasing resistance to therapeutic and other antimicrobials in Campylobacter is of public health concern. Poultry meat is still considered a major source of human infection in GB and Northern Europe. The contribution made by pig, cattle and sheep campylobacters to human infection remains unclear. VLA have implemented GB-level broiler abattoir surveillance to determine the prevalence of and levels of resistance in C. jejuni and C. coli in broiler chickens at slaughter. Use of harmonised methods is a pre-requisite for comparability of data for broiler monitoring between EU member states and will also facilitate comparisons with isolates recovered from human sources. Prescribing susceptibility test methods and antibiotics for Campylobacter spp. has proven difficult, because approved guidance documents and interpretive criteria are limited to the newest CLSI guidelines. However, multiple methods are currently used throughout the EU public health and veterinary laboratory network for the antimicrobial susceptibility testing for human, food and veterinary campylobacters. Harmonisation of methods is ugently required as the European commission gears individual countries towards monitoring of broilers for prevalence of resistant campylobacters. Use of rigorous technology for monitoring resistance will provide high quality data on which to base policy decisions. However, it is important that clinical and veterinary monitoring in GB are also harmonised and that data gathered using these methods can be compared to the data collected in recent years using those methods which had been in common use for susceptibility testing in GB public health and veterinary laboratories. The test currently used by VLA and HPA for susceptibility testing is agar incorporation at a breakpoint level. This test cannot provide quantitative trends. Commercial semi-mechanised microbroth techniques are now being used in major resistance surveillance programmes. The EFSA task force has produced a set of recommendations for antibiotics and concentration ranges and these have now been incorporated in the Commission Decision document 2007/516/EC.
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The work proposed in this project is a collaboration between the Veterinary Laboratories Agency and the Health Protection Agency and is in response to the Defra strategy for developing and implementing a programme of surveillance for antimicrobial resistance for England and Wales. This strategy has a stated objective to provide information on prevalence and patterns of resistant organisms in animals and the environment in a way that it is comparable with that from humans and animals. The proposal also reflects the ACMSF recommendations that data provided should be comparable with data produced in other EU countries to facilitate joint reporting from human and animal surveillance at EU level.
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A validation and screening exercise will be designed on the basis of the report of the task force on zoonoses data collection including a proposal for a harmonised monitoring scheme of antimicrobial resistance in Salmonella in fowl (Gallus gallus), turkeys, and pigs and Campylobacter jejuni and C. coli in broilers (EFSA Journal, 2006) and subsequently laid down in the Commission Decision document 2007/516/EC. The EU requires that detailed rules on the antimicrobial resistance monitoring of Campylobacter jejuni and Campylobacter coli in poultry are laid down. EU monitoring of broiler flocks will commence in January 2008. However, a 3 year GB survey to investigate flock prevalence of C. jejuni and C. coli in caecal contents at slaughter, based on the EU technical specifications is already underway at VLA Weybridge.
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This proposal seeks to address the harmonisation of veterinary and clinical antimicrobial susceptibility testing for C. jejuni and C. coli in England and Wales according to EU guidelines by evaluating a broth microdilution test which will be used to screen isolates recovered from humans, retail meats and broiler and pig samples from Great Britain by virtue of links to the IID survey, poultry product and submissions to the Diagnostic and Specialist Identification Unit of the Department of Gastrointestinal, Emerging and Zoonotic Infections at CFI Colindale and to abattoir surveys in broilers and pigs. The harmonised approach will then be used in human and food animal, including the Defra broiler monitoring project OZ0613, to produce data which provides exact levels of resistance from these sources to enhance accuracy of monitoring trends for campylobacters in GB and across the EU. This in turn will inform risk assessment and practical policy decisions on control of resistant Campylobacter in broiler production and in foods. The project team, which includes scientific and statistical expertise, will seek support and advice from members of the DARC subgroup, EUCAST, the European Food Safety Authority (EFSA), European Centre for Disease Prevention and Control (ECDC) and the EU Community Reference Laboratory (CRL) for antimicrobial resistance.