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An attractive method for bacteria detection
30 March 2010
Chemists have found a simple and direct way to detect a species of bacterium that can cause illness in pigs and humans.
Rapid identification and characterisation of bacterial pathogens for medical diagnosis is important to serve as an alternative to time-consuming culturing. Bacteria carry adhesion proteins on their surface, which bind to cells in the body during the infection process. These adhesion proteins are different between species and so can be used to detect bacteria. Methods to detect E. coli by identifying its adhesion proteins have been successful but until now it has not been extended to other species.
Roland Pieters and colleagues at Utrecht University, The Netherlands, have devised a method to specifically detect the adhesion proteins on Streptococcus suis, which causes meningitis, septicemia, and pneumonia in pigs, and 'has also been identified as an emerging human threat' says Pieters.
Magnetic glycoparticles binding to the surface of Streptococcus Suis
Pieters' team attached commercially available magnetic beads containing the protein streptavidin to a series of carbohydrates that were specially designed to bind to the bacterium's proteins. After mixing with the bacterium, the bacteria-bead conjugates could simply be removed using a magnet and the amount determined using a luminescence assay.
This is the first direct method of detecting S. suis, says Pieters, adding that although it was known that its adhesion proteins could bind to carbohydrates, the density of the adhesion proteins was not known. 'We have shown that there are clearly enough adhesion proteins to allow specific detection,' he states.
Suri Iyer, an expert in biosensors at the University of Cincinnati, US, is impressed by the elegant design, saying that it is 'a simple and rapid assay for the detection of pathogenic S. suis bacteria, that could, after optimisation, potentially make an impact in the swine industry.'
Pieters concludes that the method has the potential to be extended to other pathogens, and that 'in many cases the adhesion proteins are virulence factors, so positive detection may also mean that you specifically detect the dangerous ones'.
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Link to journal article
Detection of pathogenic Streptococcus suis bacteria using magnetic glycoparticles
Núria Parera Pera, Annika Kouki, Sauli Haataja, Hilbert M. Branderhorst, Rob M. J. Liskamp, Gerben M. Visser, Jukka Finne and Roland J. Pieters, Org. Biomol. Chem., 2010, 8, 2425
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