6.2. Polymerase chain reaction (PCR)
To overcome the disadvantage of MPN method for detecting V. parahaemolyticus, polymerase chain reaction (PCR) using DNA primers targeting tdh and trh genes encoding thermostable direct hemolysin (TDH) and TDH- related hemolysin (TRH), respectively, were developed for detecting virulent strains of V. parahaemolyticus. Tada et al. (1992) developed a PCR procedure for specific detection of tdh and trh and reported that the procedure was capable of detecting 400 fg of cellular DNA carrying the respective gene. However, this assay cannot be used to detect V. parahaemolyticus that does not carry tdh or trh and its sensitivity was reduced by inhibitors present in normal fecal samples. Authors suggested that either a DNA extraction or an enrichment of samples in alkaline peptone water for 4 h be conducted when analyzing fecal samples