Screening Test for Shed Skin Cells by Measuring the Ratio of Human DNA to Staphylococcus epidermidis DNA |
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| Authors: | Hiroaki Nakanishi PhD Takeshi Ohmori PhD Masaaki Hara PhD Shirushi Takahashi MD PhD Akira Kurosu MD PhD Aya Takada MD PhD Kazuyuki Saito MD PhD |
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| Institution: | 1. Department of Forensic Medicine, Juntendo University School of Medicine, Bunkyo‐Ku, Tokyo, Japan;2. National Research Institute of Police Science, Kashiwa, Chiba, Japan;3. Department of Forensic Medicine, Saitama Medical University, Moroyama, Saitama, Japan;4. Department of Legal Medicine, Dokkyo Medical University School of Medicine, Mibu, Tochigi, Japan |
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| Abstract: | A novel screening method for shed skin cells by detecting Staphylococcus epidermidis (S. epidermidis), which is a resident bacterium on skin, was developed. Staphylococcus epidermidis was detected using real‐time PCR. Staphylococcus epidermidis was detected in all 20 human skin surface samples. Although not present in blood and urine samples, S. epidermidis was detected in 6 of 20 saliva samples, and 5 of 18 semen samples. The ratio of human DNA to S. epidermidisDNA was significantly smaller in human skin surface samples than in saliva and semen samples in which S. epidermidis was detected. Therefore, although skin cells could not be identified by detecting only S. epidermidis, they could be distinguished by measuring the S. epidermidis to human DNA ratio. This method could be applied to casework touch samples, which suggests that it is useful for screening whether skin cells and human DNA are present on potential evidentiary touch samples. |
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| Keywords: | forensic science touch DNA screening test
Staphylococcus epidermidis
human DNA real‐time polymerase chain reaction |
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