title: Development of loop-mediated isothermal amplification to detect Streptococcus suis and its application to retail pork meat in Japan.
abstract: We here developed a novel loop-mediated isothermal amplification (LAMP) method to detect Streptococcus suis in raw pork meat. This method, designated LAMPSS, targeted the recombination/repair protein (recN) gene of S. suis and detected all serotypes of S. suis, except those taxonomically removed from authentic S. suis, i.e., serotypes 20, 22, 26, 32, 33, and 34. The specificity of LAMPSS was confirmed and its detection limit was 5.4cfu/reaction. Among the 966 raw pork meat samples examined, including sliced pork, minced pork, and the liver, tongue, heart, and small intestine, 255 samples tested positive with LAMPSS. The rate of contamination was higher in the organs than in pork. No significant difference was observed in the total bacterial count between LAMPSS-positive and -negative samples. The number of shops that provided LAMPSS-positive pork was slightly higher in those that sold swine organs and pork than in those that sold only pork, suggesting that cross contamination occurred from the organs to pork. Among the 255 which tested positive for LAMPSS, only 47 samples tested positive for the previously described LAMP specific for S. suis serotype 2. Two isolates of S. suis serotype 2, belonging to sequence type 28, which is potentially hazardous to humans, as well as those of some other serotypes were obtained from 19 out of 47 samples by combining LAMP with a replica plating method. These results suggest that LAMPSS will be a useful tool for the surveillance of raw pork meat in the retail market.
authors.affiliation: Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Sakura
authors.initials: S
authors.lastname: Arai
authors.affiliation: Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Tohya
authors.affiliation: Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Ryoko
authors.initials: R
authors.lastname: Yamada
authors.affiliation: Department of Bioresource Sciences, Graduate School of Agricultural Sciences, Kobe University, Rokko-dai 1-1, Nada-ku, Kobe, Hyogo 657-8501, Japan.
authors.forename: Ro
authors.initials: R
authors.lastname: Osawa
authors.affiliation: Organization for Advanced Science and Technology, Kobe University, Rokko-dai 1-1, Nada-ku, Kobe, Hyogo 657-8501, Japan.
authors.forename: Ryohei
authors.initials: R
authors.lastname: Nomoto
authors.affiliation: Department of Microbiology, Aichi Gakuin University, School of Pharmacy, 1-100 Kusumoto-cho, Nagoya, Aichi 464-8650, Japan.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kawamura
authors.affiliation: Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan. Electronic address: asekizak@mail.ecc.u-tokyo.ac.jp.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Sekizaki
mesh_terms: D000818:Animals; D058491:Bacterial Load; D005516:Food Microbiology / Q000379:methods*; D007564:Japan; D008460:Meat / Q000382:microbiology*; D021141:Nucleic Acid Amplification Techniques; D012680:Sensitivity and Specificity; D017011:Streptococcus suis / Q000235:genetics* / Q000302:isolation & purification; D013552:Swine
keywords: LAMP; Pork; Streptococcus suis