cefoxitin and Fish-Diseases

Pure bacterial cultures were isolated from diseased snakeheads, Channa maculata (Lacepède), suffering high mortality in a farm in Zhongshan, southern China. Three isolates, namely ZS20100725, ZS20100725-1 and ZS20100725-2, were identified as Aeromonas schubertii. All the isolates showed high 16S rRNA sequence similarities with A. schubertii. The isolates exhibited strong virulence to snakeheads in experimental challenges with LD(50) ranging between 1.4 × 10(4) and 6.4 × 10(6) CFU g(-1). Two of the isolates were positive for haemolysin, elastase, lipase and lecithinase by phenotypic determination, which was further confirmed by PCR amplification of the haemolysin and elastase genes. In sterile liquid medium, the best growth conditions of strain ZS20100725 were 30 °C, pH 7 and 0.5% salinity (w/v). Antibiotic susceptibility tests showed that strain ZS20100725 was susceptible to cefoxitin, cefoperazone and chloramphenicol. Furthermore, histopathology of diseased snakeheads infected with A. schubertii showed necrosis and congestion in liver, kidney and spleen and also damage to the cardiac muscle, intestine and gills.

Topics: Aeromonas; Animals; Base Sequence; Cefoperazone; Cefoxitin; China; Chloramphenicol; Computational Biology; DNA Primers; Fish Diseases; Hemolysin Proteins; Lethal Dose 50; Molecular Sequence Data; Pancreatic Elastase; Perciformes; Polymerase Chain Reaction; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Species Specificity; Temperature; Virulence; Virulence Factors; Viscera

Topics: Animals; Anti-Bacterial Agents; Catfishes; Drug Resistance, Bacterial; Drug Resistance, Multiple, Bacterial; Edwardsiella ictaluri; Enterobacteriaceae Infections; Fish Diseases; Molecular Sequence Data; Plasmids; Thiamphenicol