Black rockfish (Sebastes schlegeli) is an important mariculture species in Korea. The production of this fish is drastically declined due to bacterial diseases, particularly streptococcosis caused by Lactococcus garvieae. The bacterial surface characteristics of SJ7 and TY6 were found to have capsule but not NB13 and YS18. The experiential evaluation of L. garvieae pathogenicity, the capsular isolates showed high cumulative mortality i.e. SJ7 (100%) and TY6 (60%) compared to non-capsular isolates. Based on this result the capsular isolates L. garvieae were highly suspected as the causative agent of streptococcosis in rockfish.
Agglutination Tests/veterinary ; Animals ; Bacterial Capsules ; DNA, Bacterial/genetics/isolation&purification ; Fish Diseases/*microbiology/mortality ; Fishes ; Fluorescent Antibody Technique, Indirect/veterinary ; Gram-Positive Bacterial Infections/microbiology/mortality/*veterinary ; Lactococcus/*pathogenicity ; Polymerase Chain Reaction/veterinary

OBJECTIVETo investigate a case of mass mortality of Garra rufa (G. rufa) from a fish hatchery farm in Slovakia.

METHODSCausative bacterial agent was swabbing out of affected fish skin area and subsequently identified using commercial test system. Antibiotic susceptibility was determined by the disk diffusion method.

RESULTSInfected G. rufa was characterized by abnormal swimming behaviour, bleeding of skin lesions and local haemorrhages. Despite of using recommended aquatic antibiotic treatment no improvement was achieved and Aeromonas sobria (A. sobria) was identified as a causative agent of fish mortality. Due to massive fish mortality, antibiotic susceptibility of pure isolated culture of A. sobria was evaluated employing eight antibiotics against human infections. A. sobria was resistant only against one antibiotic, namely ampicilin.

CONCLUSIONSThese results indicate that A. sobria can act as a primary pathogen of G. rufa and may be a potential risk factor for immunodeficient or immunoincompetent patients during the ichthyotherapy.

Aeromonas ; drug effects ; pathogenicity ; Ampicillin ; pharmacology ; Animals ; Anti-Bacterial Agents ; pharmacology ; Bacterial Typing Techniques ; Cyprinidae ; microbiology ; Drug Resistance, Bacterial ; Fish Diseases ; drug therapy ; microbiology ; mortality ; Fisheries ; Microbial Sensitivity Tests ; Slovakia