DAO 49:139-144 (2002)  -  doi:10.3354/dao049139

ABSTRACT: Two Aeromonas salmonicida-specific polymerase chain reaction (PCR) tests and 1 A. salmonicida subsp. salmonicida-specific PCR test were used to screen salmonid populations that were either overtly or covertly infected with A. salmonicida subsp. salmonicida. It was demonstrated that these PCR assays could be used to replace the biochemical testing currently employed to confirm the identity of A. salmonicida isolates cultured from infected fish. The AP and PAAS PCR assays were also capable of direct detection of A. salmonicida in overtly infected fish, with mucus, gill and kidney samples most likely to yield a positive result. Culture was a more reliable method for the direct detection of A. salmonicida in covertly infected salmonids than was the direct PCR testing of tissue samples, with the AP and PAAS PCRs having a lower detection limit (LDL) of approximately 4 x 10⁵ colony-forming units (CFU) g^-1 sample.

KEY WORDS: Aeromonas salmonicida · Polymerase chain reaction · Detection · Identification · Validation · Naturally infected fish · Covert infections