Future Perspective

A search of the PubMed database (www.pubmed.com) showed that at the time of writing, there had been 662 research papers published which described molecular methods (PCR-, real-time-PCR- and NASBA-based methods) for detection of the above pathogens in meat and meat products (Fig. 16.1). Considering the total effort underlying each scientific publication (researchers' salaries, materials and reagents, etc.), one may make an assumption that the total cost behind each paper is around 10, 000-20,000 euros. Thus, the overall activity which has resulted in all these methods is around 6-13 million euros. The ultimate source of research funding is the taxpayer, and the taxpayer as consumer is the prime stakeholder in every food safety research endeavour. However, the outcomes of the 6-13 million euros have not for the most part been translated into tangible benefits for the prime stakeholder. This is because very few if any of the accrued methods have been transferred from the researcher/developer's laboratory to the analyst's laboratory. Therefore, the stakeholder is not getting an adequate return for their investment.

Why is this? The typical response to this question has been that the cost of the equipment and reagents is high and it is difficult to find adequately trained personnel. However, year on year a wider choice of new platforms for real-time PCR is becoming available (from only two or three types of equipment in the late 1990s to more than 20 available in the market currently), and there are many biotechnology companies now which offer high-quality reagents and

Daily Census Graph
Fig. 16.1 A PubMed search using ''real-time PCR'', ''PCR'' and ''NASBA'' for the main meat bacterial pathogens reviewed in this chapter, sorted by year of publication

enzymes. In addition, more than 10 years have passed since the first publication in real-time PCR in 1996, and increasing numbers of trained analysts exist. So, what are the current underlying reasons hindering the adoption of these powerful methods? They are their lack of international validation in comparison with the culture-based microbiological standards, and even more importantly the food industry's lack of acceptance of them. For example, the industry is reluctant to accept PCR-positive results as unequivocal proof that a sample is contaminated with the analyte pathogen: they would insist that any such results are confirmed by conventional culture of the sample. Therefore, an advantage of the molecular-based methods, rapidity of producing results, would appear to be lost. However, this could be turned to advantage by promoting the use of PCR-based methods in screening of samples: PCR-negative samples could be cleared for consumption while positives undergo confirmation.

Ultimately, there needs to be a focused drive towards taking proven methods from the scientist's laboratory and implementing them in actual use in the analyst's laboratory. However, further developments are needed for an effective implementation of amplification techniques in food microbiology. Among the main issues that must be addressed for the effective adoption of molecular techniques by food analysis laboratories are the development of rational and easy-to-use strategies for sample treatment, and greater automation of the whole analytical process. The absolute prerequisite for successful adoption of molecular-based diagnostic methodology is international validation and subsequent standardization (Hoorfar & Cook, 2003; Malorny, Tassios, et al., 2003; D'Agostino & Rodriguez-Lazaro, 2009). Most analysts still regard the conventional ''gold standard'' culture-based methods as the only accepted method. Therefore, any molecular-based method should be shown to work at least as well as the corresponding conventional method, by direct comparison of the analytical performance of each on identical food samples. There is an international standard guideline for performing this validation (Anonymous, 2003a). Standard guidelines regarding the use of PCR for the detection of foodborne pathogens have also been established (Anonymous, 2005a, 2005b, 2006a, 2006b). Finally, a determined effort to promote dialog between the researcher and the analyst is necessary, to encourage and mediate adoption of fit-for-purpose methodology. Ideally, this effort requires the establishment of a solid international infrastructure for taking promising analytical methods through development and validation and finally delivering them for use. The foundation of this scenario awaits support from international funding agencies.

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