Identification of Aeromonas salmonicida in European perch from North Lithuanian rivers during mass mortalities in 2008

Abstract

Abstract:The investigation was carried out to ascertain the cause of mass mortalities in European perch (Perca fluviatilis L.) in NorthLithuanian rivers in 2008 that reached a maximum in mid-autumn at a water temperature of 6ºC. Marked changes were detected in morphophysiological parameters (spleen-, gill-, liver-and heart-somatic indices), which corresponded to changes in haematological parameters (leukocyte count was significantly elevated or reduced) of the infected fish. The viable bacterial counts in the gill, liver and kidney of infected live fish samples ranged from 2.3±0.3 x 10 3 to 6.3±0.4 x 10 3 c.f.u./g. The BOX-PCR fingerprinting technique was used for characterization and identification of the isolated bacterial strains from liver and kidney of infected perch. The bacterial isolates were identified by sequence analysis of the 16S rRNA gene. Pathogenic Aeromonas salmonicida subsp. salmonicida has been identified as a possible causative agent of the observed mortality in European perch.

Aeromonas salmonicida infected fish transfer disease to healthy fish via water

“…Furthermore, the differences in immune responses of infected fish could depend on their physiological state and disease duration [29]. Similar different alterations in WBC counts were found in our previous study with perch naturally infected with A. salmonicida [1].…”

“…Afterwards, dark-brown colonies were selected and restreaked three times onto fresh media to obtain pure isolates. A. salmonicida was identified by DNA extraction, REP-PCR, amplification and sequencing of 16S rRNA gene [1]. After 8 days incubation count of dark-brown colonies on TSA from tested fish have been repeated.…”

“…The present investigation of the experimental infection is a continuation of our previous study [1], and referred to the transmission and impact of infection with Aeromonas salmonicida subsp. salmonicida of European perch and sea trout.…”

“…Pathogenic Aeromonas salmonicida subsp. salmonicida were identified as a possible causative agent of fish disease -septicaemia, which usually resulted in high mortality rates [1]. The bacterial isolates were identified by sequence analysis of the 16S rRNA gene [1].…”

“…salmonicida were identified as a possible causative agent of fish disease -septicaemia, which usually resulted in high mortality rates [1]. The bacterial isolates were identified by sequence analysis of the 16S rRNA gene [1]. Whilst European perch (Perca fluviatilis L.) are commonly widespread in European water bodies, data available on this disease in wild perch are scarce.…”