Jpn. J. Infect. Dis., 65 (2), 111-116, 2012

To see a printable version of the article in the Adobe file format, click this [PDF] link.

Mitsugu Yamazaki^1,3, Hidemi Aoki^1,3, Yoshito Iwade², Masakado Matsumoto³*, Kazuhiro Yamada³, Hiroaki Yamamoto³, Masahiro Suzuki³, Reiji Hiramatsu³, and Hiroko Minagawa³

¹Laboratory of Microbiology, Aichi Prefectural Kinuura-Tobu Health Center, Kariya 448-0857; ²Microbiological Research Section, Mie Prefectural Health and Environment Research Institute, Yokaichi 512-1211; and ³Department of Microbiology and Medical Zoology, Aichi Prefectural Institute of Public Health, Nagoya 462-8576, Japan

(Received September 9, 2011. Accepted November 25, 2011)

*Corresponding author: Mailing address: Department of Microbiology and Medical Zoology, Aichi Prefectural Institute of Public Health, Nagare 7-6, Tsuji-machi, Kita-ku, Nagoya, Aichi 462-8576, Japan. Tel: +81-52-910-5669, Fax: +81-52-913-3641, E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

SUMMARY: We developed an enrichment medium for use with the loop-mediated isothermal amplification (LAMP) assay (enrichment media + LAMP assay) to quickly increase a very small number of Vibrio parahaemolyticus cells to the detection limit of the assay. Thirty-nine different enrichment media were prepared based on evaluating 12 potential ingredients. From our assessment of the 39 media, enrichment medium #36, which contained 2% sodium chloride, 1% proteose peptone no. 2, 0.1% trehalose, 0.5% α-ketoglutaric acid, 0.25% pyruvic acid, and 0.5% yeast extract (pH 8.6), was found to be most effective at enhancing the proliferation of V. parahaemolyticus during incubation for 3 h at 40°C. We compared the detection limits of the LAMP assay, the enrichment medium #36 + LAMP assay, and the cultivation method using bacterial cell and spiked shrimp sample tests. The detection limits of the LAMP assay, the medium #36 + LAMP assay, and the cultivation method were 10³, 10⁰–10^-1, and 10^-1 CFU ml^-1, respectively. Enrichment medium #36 promoted a 10³- to 10⁴-fold increase in the bacterial population, and the detection limit of the enrichment media + LAMP assay was the same as that of the cultivation method.