Yersinia enterocolitica as a cause of septicemia in crucian carp (Carassius carassius)

Yersinia enterocolitica is an important pathogen to animals and humans. Thirteen strains of Y. enterocolitica were isolated from diseased fish. The partial 16SrDNA gene, five virulence genes, pathogenicity, and drug resistance of Y. enterocolitica strain G6029 were studied using molecular biological technology and toxicological method. Results showed that the length of amplified 16SrDNA sequence was 1448bp, and revealed 99% homology with Y. enterocolitica. Its GenBank accession number was JX855135. Five virulence genes (ail, ystB, yadA, virF and HPIint) were detected, and only yadA gene was not seen. Twenty-eight crucian carps that were injected with strain G6029 died within a week, and the mortality was 93.3%, indicating highly pathogenic attribute of this strain. In addition, the strain G6029 was resistant to four antibiotics (sulfafurazole, furazolidone, enrofloxacin and norfloxacin), but it was susceptible to six antibiotics (florfenicol, vibramycin, cefaloridine, ciprofloxacin, streptomycin, and ampicillin). Further study of pathogenicity of Y. enterocolitica in teleost fish is suggested.