Detection and identification of Aeromonas hemolysin and aerolysin genes by amplification of fragments in the multiplex PCR assay. Lanes 1 and 9, 100-bp ladder (Invitrogen); lane 2, A. hydrophila genotype 1 showing the ahh1 and 16S rRNA genes (130- and 356-bp fragments, respectively); lane 3, A. hydrophila genotype 4 showing the ahh1, aerA, and 16S rRNA genes (130-, 309-, and 356-bp fragments, respectively); lane 4, A. sobria gentotype 2 showing the asa1 and 16S rRNA genes (249- and 356-bp fragments, respectively); lane 5, A. sobria genotype 3 showing the ahh1, asa1, and 16S rRNA genes (130-, 249-, and 356-bp fragments, respectively); lane 6, 16S rRNA internal control showing a 356-bp fragment only; lane 7, PCR positive control with a DNA mixture showing PCR amplification fragments for all four genes, ahh1, aerA, asa1, and 16S rRNA (130-, 309-, 249-, and 356-bp fragments, respectively); lane 8, PCR negative control.