Molecular Diagnostics for Infectious Gastroenteritis

Diarrheal disease is mostly caused by an infection with a bacteria/virus/parasite (infectious gastroenteritis). Worldwide these infections are responsible for a considerable morbidity and mortality. In fact, after RTI (respiratory tract infections), diarrheal disease is the second most common infection worldwide! Diarrheal disease occurs mainly in developing countries (especially amongst young children, but infectious gastroenteritis is also responsible for a considerable socio-economic impact in industrialised countries. Defining the microbiologic causes of diarrheal disease is challenging due to the large number of potential enteropathogens that require testing. Currently, conventional diagnostic procedures (such as culture, EIA and microscopy) still remain the cornerstone for routine detection of bacterial and parasitic enteropathogens in medical microbiology laboratories worldwide. However, these methods are labour intensive and final results are not available until 3-4 days after sample processing. Furthermore, the majority of the samples do not yield a positive result. Another disadvantage of conventional techniques is the suboptimal performance with regards to sensitivity and specificity. Molecular techniques (detection of genetic material -DNA/RNA- of potential enteropathogens), such as real-time PCR, may play an important role in routine diagnostics for infectious gastroenteritis; these methods are fast (<24hours) and can provide a reliable result with a high sensitivity and specificity. Because these methods can provide results very fast, they can improve adequate actions that need to be made in case of major outbreak situations. Another advantage is the improvement of “workflow” in the laboratory (as these methods are less labour-intensive). The scope of this thesis was the explore the possibilities to incorporate molecular assays into diagnostic algorithms for reliable detection of primarily non-viral enteropathogens in the clinical microbiology laboratory. Conclusions: It is feasible to apply molecular assays (real-time PCR) as a fast (cost-effective) and efficient primary screening tool for detection of enteropathogens. The molecular methods can be incorparated into diagnostic algorithms and conventional techniques will only be applied in case the results of the molecular assays warrents further testing; this means that conventional methods are only applied for positive samples in order to confirm the molecular results and also for resistance profiling in case of bacterial infections.

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