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A Simple Identification Method of Saliva by Detecting Streptococcus salivarius Using Loop-Mediated Isothermal Amplification

Authors

  • Hiroaki Nakanishi Ph.D.,

    1. Forensic Science Laboratory of Yamanashi Prefectural Police H.Q., 312-4 Kubonakajima, Isawa, Fuefuki, Yamanashi 406-0036, Japan.
    2. Department of Forensic Medicine, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan.
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  • Takeshi Ohmori Ph.D.,

    1. National Research Institute of Police Science, 6-3-1 Kashiwanoha, Kashiwa, Chiba 277-0882, Japan.
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  • Masaaki Hara Ph.D.,

    1. Department of Forensic Medicine, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan.
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  • Aya Takada M.D.,

    1. Department of Forensic Medicine, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan.
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  • Hideki Shojo Ph.D.,

    1. Department of Legal Medicine, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
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  • Noboru Adachi M.D.,

    1. Department of Legal Medicine, Faculty of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan.
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  • Kazuyuki Saito M.D.

    1. Department of Forensic Medicine, Faculty of Medicine, Saitama Medical University, 38 Morohongo, Moroyama, Saitama 350-0495, Japan.
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Additional information and reprint requests:
Hiroaki Nakanishi, Ph.D.
Forensic Science Laboratory of Yamanashi Prefectural Police H.Q.
312-4 Kubonakajima
Isawa
Fuefuki
Yamanashi 406-0036
Japan
E-mail: nakanishi@384.jp

Abstract

Abstract:  We previously reported that detection of Streptococcus salivarius is feasible for proving the presence of saliva in a forensic sample. Here, a simple and rapid method for the detection of S. salivarius in forensic samples was developed that uses loop-mediated isothermal amplification (LAMP). The LAMP primer set was designed using S. salivarius-specific sequences of glucosyltransferase K. To simplify the procedure, the sample was prepared by boiling and mutanolysin treatment only, and the entire analytical process was completed within 2.5 h. The cut-off value was set at 0.1 absorbance units, measured at 660 nm, upon termination of the reaction. S. salivarius was identified in all saliva samples, but was not detected in other body fluids or on the skin surface. Using this method, S. salivarius was successfully detected in various mock forensic samples. We therefore suggest that this approach is useful for the identification of saliva in forensic practice.

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