Characterization of Erysipelothrix rhusiopathiae strainsisolated from acute swine erysipelas outbreaks in Eastern China

[摘要] References(23)Cited-By(2)Supplementary materials(1)Recently, a series of acute swine erysipelas outbreaks occurred in Eastern China. Eightstrains isolated from cases of septicemia were determined as serotype 1a, and 4 of theisolates were resistant to acriflavine. One isolate strain named HX130709 was attenuatedon agar media containing acriflavine dye. The 432-bp hypervariable region inspaA gene of the field and attenuated strains were amplified andsequenced. It was further compared with the vaccine strain G4T10,and thus, the eight field strains can be divided into four spaA-types.The partial spaA gene analysis also showed that no point mutationsoccurred among different archived passages of HX130709 during the attenuation. Results ofpulsed-field gel electrophoresis showed that eight distinct patterns with 22 to 30 DNAfragment bands were produced from field strains, and twelve distinct patterns with 23 to27 DNA fragment bands were produced from different passages of the attenuated strains.Mouse pathogenicity test showed that the mortality of the mice infected with104 CFU field strains was 100% and the attenuation of strain HX130709occurred between 46 and 50 passages. All the field and attenuated strains were highlysensitive to β-lactam antibiotics, tetracyclines and macrolides. So, we can makeconclusions that the acute swine erysipelas outbreaks in Eastern China were caused byserotype 1a E. rhusiopathiae strains with different biochemicalcharacteristics, and the virulence of serotype 1a E. rhusiopathiaestrains is unrelated with some point mutations in 432-bp hypervariable region of thespaA gene.

[学科分类] 兽医学

[关键词] acriflavine;attenuation;Erysipelothrix rhusiopathiae;PFGE;spa