Detection of TDH-producing Vibrio parahaemolyticus O3:K6 from naturally contaminated shellfish using an immunomagnetic separation method and chromogenic agar medium]

We attempted to isolate TDH-producing Vibrio parahaemolyticus O3:K6 from shellfish. Asari samples were incubated with TSB supplemented with 2% (w/v) NaCl for 6 h, and then the 6-h cultures were incubated with salt polymyxin broth for 18 h. After the two-step enrichment, a 1 ml portion of the culture was treated with magnetic beads coated with K6 antibody for immunoconcentration of V. parahaemolyticus O3:K6. The immunoconcentrated and untreated cultures were plated onto a chromogenic agar and TCBS agar media for isolation of V. parahaemolyticus. TDH-producing V. parahaemolyticus O3:K6 was isolated from 3 out of 66 lots (4.5%) of naturally contaminated Asari. Six of 4,265 colonies suspected as V. parahaemolyticus (0.14%) were TDH-producing V. parahaemolyticus O3:K6.