Middle Ear Membrane

The reservoirs of Campylobacter spp. in the environment are extensive and include wild and domestic birds and animals. Despite this, there are examples of production facilities that rear infection-free stock, through use of strict hygiene and control procedures and practices, and through sourcing pathogen-free materials. In some countries, there has been sufficient motivation and resources, from government and the animal/poultry production industry, to realise Campylobacter-free production at the farm level. The public health impact of providing Campylobacter-free animal/poultry produce is unclear, however. In many regions where this produce is consumed, the incidence of campylobacteriosis remains high and there are likely to be other sources of infection that will still cause significant morbidity.

Public awareness of some of the hazards associated with foods has been increasing in the past 20 years. However, since large outbreaks of campylobac-teriosis are relatively uncommon or go unrecognised, Campylobacter rarely hits the headlines in the popular press and public awareness of this pathogen is probably still relatively small. With better methods, particularly genotypic, for the characterisation of microorganisms (e.g. genetic 'fingerprinting') and common standardised approaches being used and synchronised in the investigation of foodborne diseases, there is likely to be an increasing number of links made between 'sporadic' cases of illness. The low biochemical activity of Campy-lobacter spp. and frequent variability made characterisation/identification on the basis of phenotype very difficult. This difficulty has hampered epidemiological investigations and our understanding of the incidence and behaviour of Campylobacter spp. in the environment and animals. The development in molecular methods has changed bacterial diagnostics and taxonomy. At present the methods available have different pros and cons, and a combination of methods is needed to secure identification of all Campylobacter spp. These methods will continue to be developed and refined to enable more reliable characterisation/identification to be carried out in non-specialist laboratories.

With Arcobacter spp., there is currently little direct evidence of this group causing foodborne illness. However, since the organisms are known to cause disease in animals (including humans) and have been associated with meat and poultry products, there seems little doubt that they should be regarded as potential foodborne pathogens. Methods for characterisation/identification, as for Campylobacter spp., are being improved in terms of specificity and sensitivity. The trend towards use of molecular techniques has also enabled identification and direct detection of virulence genes, in isolates from different environments. This ability of linking pathogenicity markers (virulence factors) to isolates was not possible with the more classical characterisation techniques.

The impact of molecular approaches is also important for understanding patho-genesis. Since genotypic methods are becoming reliable and easily employed, genotypic analysis of isolates from different reservoirs should indicate whether animals (including humans) and birds share the same bacterial populations or whether there are sub-populations only pathogenic to susceptible groups or hosts. The genomic sequence of C. jejuni is now available and if homology with genes known to be responsible for virulence traits (e.g. invasiveness or toxin production) is identified, a better understanding of pathogenesis can be expected.

Another trend that deserves further elaboration is the change in surveillance strategies. Existing surveillance systems in many countries are limited and will only detect outbreaks of established and easily recognised pathogens. Both national and international surveillance strategies are now being enhanced by employing common, standardised sub-typing techniques and also by more active surveillance of populations. For example, in the USA, FoodNet has been designed as a platform to collect/collate information from different sources (e.g. case-control studies) so that true disease incidence can be determined. These efforts will result in identification of diffuse outbreaks that may have little impact on a local basis, but when taken together with other related cases, may have a much bigger impact. Immediate responses to these outbreaks will result in product recalls and longer-term activities will focus on prevention of future similar outbreaks. Environmental sampling and end-product testing is another trend that is increasing in some countries, and detection of campylobacters will be facilitated through development of new approaches and techniques.

The antibiotic resistance profile of isolates associated with foodborne illness is another feature that will be determined in surveillance activities. The development of antibiotic resistance in campylobacters has been attributed, at least in part, to the use of antibiotics in agriculture. This has led to the banning of par ticular types of antibiotics for some uses in agriculture and more restrictive controls are likely to be implemented both in veterinary and human medicine in the future.

With campylobacters, as for many other enteric pathogens, there are a number of measures that may be used for control. If used independently, these measures are often not sufficient to reduce the risk of infection to an acceptable level, and combinations of measures are necessary. For many national and international regulatory bodies, the emphasis is increasingly towards an integrated approach to food safety. For campylobacters, this means looking at reservoirs, where future control measures may include selective sourcing of 'clean' raw materials and feed, changing hygienic practices on the farm, modification of the slaughter process and consideration of alternative processing technologies, such as irradiation. Many of these changes and improvements come with a price and successful implementation will be dependent on an acceptance by the consumer and producers that these changes are a real benefit to them.

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