Steven Meikle - The rapid and specific real-time detection of Legionella pneumophila in water samples using Optical Waveguide Lightmode Spectroscopy

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      Cooper, I.R., Meikle, S.T., Standen, G., Hanlon, G.W., Santin, M.   78 (1) 40-44

      Abstract: The detection of Legionella   pneumophila in water samples using standard microbiological   culture techniques is both prolonged and problematic. The   bacterium is slow-growing and nutritionally fastidious, such that   other indigenous species can out-compete the Legionella even when   using antibiotic supplemented media. Optical Waveguide Lightmode   Spectroscopy (OWLS) is a real-time analytical system whereby a   change to a higher coupling angle where the refractive index of a   bacterial cell is higher than that of the covering medium. In   this study an aqueous suspension of L. pneumophila was passed   across the surface of waveguides functionalised with a specific   anti-Legionella antibody. The binding between the bacterial cells   and the antibody specific for that cell resulted in an increase   in the refraction indices of the transverse electric and   transverse magnetic photoelectric currents. We report the   optimisation of a rapid and sensitive (1.3 × 104 CFU mL− 1)   detection method for L. pneumophila contamination in a water   sample in less than 25 min. This is a significant reduction   in the time taken to determine the presence of the bacterium   which with conventional techniques normally takes up to fourteen   days. In addition, the specificity of the technique to L.   pneumophila was demonstrated. The OWLS results were validated by   conventional microbiology screening and atomic force microscopy   of the surface of the waveguide, showing its species specificity   and potential applications in environmental and clinical   analysis.

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