One hour service

The mere thought of a rapidly spreading epidemic is enough to put anyone on edge, particularly the lab technicians and public health officials who must race against time to identify and contain the disease before panic and loss of social order ensues. As it stands, it can take up to ten days using the conventional plating method to detect and determine the source of contamination for Legionnaire¡¯s disease, and around three days for Listeria. In that time, a fair amount of people could get infected and lives could be at stake. In the case of food contamination, products would have already made their way to the shelves of grocery stores and fridges of consumers, which would result in costly product recalls.

Imagine it were possible to obtain accurate detection results within one hour. A speedy but precise analysis would significantly decrease the likelihood of a disease epidemic, and increase prevention of food and water related outbreaks of pathogenic organisms. external page rqmicro, an ETH spin-off promises such a fast delivery. ¡°The idea behind rqmicro, which stands for Rapid Quantitative MICRObiology, was to modernise the current microbe detection methods by developing an on-a-chip detection system¡±, explains Hans-Anton Keserue, PhD of Microbiology at ETH Zurich and founder of the company, ¡°With our technology, we are able to integrate manual methods on a microfluidic device that has the capability to produce result in one hour.¡±

Have a little patience

The standard established methods to count, detect and quantify bacteria are often still based on calculation. Most of us remember the procedure from our high school biology class: a sample of water, for instance, is taken and placed on an agar plate, bacteria present in water then grow on solid nutrient media (incubated at a warm temperature), and finally, the little colonies that form are counted. This classic microbiology method conducted in three steps ¨C filtration, cultivation and identification ¨C can take at least 72 hours.

¡°For Legionella pathogens, which sometimes occur in drinking water in high concentrations, culturing can last ten days¡±, Keserue clarifies, ¡°So usually, it really takes patience to examine food or drinking water for particular bacteria, and in many cases, it¡¯s like looking for a needle in haystack of background flora.¡± While waiting to see what grows in a petri dish may have been exciting as a teenage student, in a situation where lives are on the line, durations of up to three days or more can be detrimental.

Quick and accurate

Until now, lab technicians have only been able to examine pathogens by cultivating them. This is where rqmicro takes microbe quantification to a new level: their sample preparation relies on microfluidic technology. Essentially, a sample is applied to specially developed antibodies that are equipped with magnetic nanoparticles. The targeted pathogens are then separated by magnetic force, creating highly purified target cells that are easy to be measured on commercial flow cytometers, devices that are able to analyze several thousand particles a second in real time. ¡°Not only does our method lead to results much faster than before, it is also more reliable¡±, asserts Keserue. This method also allows for quantification of bacteria that do not grow in cultivation, but are still potentially infectious.

rqmicro is already offering their method for rapid quantification of Legionella in water as a service to clients and industry partners. But they have big plans for the future. The first step is to bring a benchtop instrument for automated immunomagnetic labeling and separation onto the market. This can be used to purify pathogens as well as any other type of cell. Long-term plans include the integration of a detection system in a second generation of instruments. ¡°Our overall goal is to market our methods and detection systems as products to laboratories that test food and drinking water for bacteria¡±, says Keserue.

Officially approved

rqmicro is based on Keserue¡¯s dissertation on quick detection of pathogens with the help of external page Flow Cytometry (FCM), which he wrote during his time at Eawag. FCM is a laser-based electronic cell counting technology, whereby the quantification of cells in any given sample can be performed in a matter of minutes. This cultivation independent method allows all bacteria, dead or alive, to be quantified. Using special fluorescent dyes, viable cells can also be distinguished from dead or dormant ones.

FCM provides much more realistic results than the conventional methods and is now being officially used for the quantification of the total load of microbial cells in drinking water. This new analytical method ¨Cwhich was further developed and optimised at Eawag and extensively tested both in Switzerland and abroad ¨C has been incorporated into the Swiss Food Compendium (SLMB) by the Swiss Federal Office of Public Health (FOPH).