How low can you go: low detection limits

How do you detect a single bacterium among millions of DNA fragments? And how do you reliably determine whether an analysis technique truly meets increasingly stringent standards?

During this seminar, two experts will provide insights and experiences.

Finding the Needle in a Haystack of DNA: Ultra-Sensitive Detection of E. coli and Enterococci in Drinking Water.

Drinking water is tested daily for traces of faecal contamination. According to the legal standard, drinking water may not contain any E. coli or enterococci—one bacterium of this species is already too many. Traditional culture methods are used by drinking water laboratories for this purpose, but these require relatively long analysis times and are limited in sensitivity and specificity. As an alternative, we have developed molecular detection techniques, such as PCR-based methods, that can demonstrate the presence of faecal indicator organisms faster and with higher sensitivity. However, the challenge remains: detecting the presence of a single E. coli or enterococci in a background of millions of other DNA fragments requires very robust and validated analysis methods.

In this talk I will share our experiences with the development and validation of such molecular methods. I will discuss how we managed to reach the detection limits required by law, which technical and practical obstacles we encountered, and which lessons we learned with a view to future applications in drinking water diagnostics.
Speaker: Adrie Atsma from Vitens

Back to basics
Analytical techniques are becoming increasingly sensitive, and international legislation is evolving just as rapidly, with ever-lower maximum residue levels (MRLs) for contaminants, for example. Many statistical methods are available for reliable validation or demonstrating that an analysis can quantify at MRL level. But how do you choose the right statistical method and experimental setup for the right technique? And how confident are you that your calculated performance is representative and realistic? This session will help you gain insight into the basic principles behind determining a detection limit, using various guidelines and statistical methods. You will gain various tips and tricks based on several case studies.
Speaker: Rick Wolf of TLR

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