For the food industry, being able to detect the presence of pathogens such as Salmonella, Listeria and Ecoli is vital. And the faster this is achieved, the better.

Because of this need for speed, most conventional rapid techniques only analyse a fraction of the standard 25g sample. However, a new system developed by Matrix Microscience circulates and analyses the entire sample and so gives a much more accurate assessment of pathogen presence.
At the heart of this new system, which is known as Pathatrix, is a peristaltic pump supplied by Watson-Marlow. It is easy and quick to use, does not require cleaning or maintenance and guarantees no cross contamination between samples (Fig.1).
Each Pathatrix system consists of five independent testing stations within one housing, so there are five off-the-shelf 313D series pumpheads per machine.
Matrix Microscience also produces proprietary consumable packs that include a length of tubing for use in the pumphead. This means that the tubing in the pumphead is only ever used for one sample, thereby eliminating the risk of cross-contamination.
Furthermore, with the tubing made from a compliant silicone rubber, the instruments are capable of analysing an extremely wide variety of food samples, from milk and yoghurt to acidic products and solid samples -- such as ground beef -- that are homogenised with the 225ml of liquid growth media.
Another element of the recirculated medium is the Pathatrix capture reagent, which consists of magnetic particles that are coated with an antibody specific to the target pathogen. Once loaded, the Pathatrix workstation runs for 180minutes at the desired incubation temperature -- from 30 to 37ºC -- with the pump circulating the fluid within a closed loop to ensure complete incubation.

After the incubation step is finished, the target microorganisms, now captured by the reagent, are magnetically restrained while the residual debris and other unwanted material is removed when the peristaltic pump operates again for the wash step.
The capture phase is then removed from the system and is further processed so that pathogen colonies can be viewed within 16hours of the start of the analysis. This is a significant saving compared with the two days or so that is usually required, and there is an additional benefit in that the sample is not contaminated with non-target organisms.
Independent tests have shown the Pathatrix system to be 221percent more sensitive than the standard United States Department of Agriculture Food Safety and Inspection Service (USDAFSIS) method, as well as being quicker and requiring only minimal hands-on time, unlike the labour-intensive alternatives. As a result of the tests undertaken at Campden and Chorleywood Food Research Association in the UK, the Pathatrix system has now received Association of Official Analytical Chemists R1 Validation.
Adrian Parton, md of Matrix Microscience, said: "One of the benefits of the Pathatrix system is that it needs only around two minutes of hands-on time, and the 313D pumphead's flip-top design and automatic tube tensioning are perfect in this respect."
Whereas the food standards in USA are driven by the USDA FSIS, there is no equivalent body in the UK. Instead, the supermarket chains tend to lay down their own quality standards, including zero tolerance for certain pathogens, which is understandable, because Listeria, Salmonella and E.coli can all be fatal for vulnerable groups such as the young, elderly and infirm.
Furthermore, with many perishable fresh foods having a short shelf life -- sandwiches are a good example -- there is a need for cost-effective, rapid testing. So Pathatrix meets the demands of supermarket chains, as well as food manufacturers, livestock breeders and contract laboratories.