Study of molecular subtypes of biotype 1A Yersinia enterocolitica in Shandong province from 2008 to 2009

Objective To investigate the molecular subtypes of 73 strains of Yersinia enterocolitica biotype 1A isolated in Shandong province by PFGE,and thereby to analyze the relationship between PFGE typing and biological characteristics.Methods Seventy-three strains of Yersinia enterocolitica biotype 1A were isolated from animal feces and meat pnoducts in Gaomi city and Wulian county in Shandong province from 2008 to 2009.Motility test,serum agglutination and virulent genes detection by PCR were used to learn the biological characteristics of the isolated strains.The molecular subtypes were determined by PFGE,whose relationships with motility,serotypes and virulent genotypes were also analyzed.Results Out of the 73strains of Yersinia enterocolitica,5 showed medium-active motility while the other 68 showed well-active motility.The dominated serotypes were O∶ 5 (17/73) and O∶ 8 (14/73),followed by O∶ 9 (5/73) and O∶ 7,8(1/73),and there was no O∶ 3 serotype found.Meanwhile,36 strains couldn't be serotyped.All the strains were negative with the gene ail,ystA,yadA and virF,yet the positive rate of ystB gene was 72.6％(53/73).The 73 strains of Yersinia enterocolitica isolated could be subtyped into 54 PFGE patterns (K6GN11SD0001-K6GN11SD0054),most of which only had 1 or 2 isolated strains,and no pattern was dominant.The strains in the same or similar cluster were from different hosts; each serotype and toxic genotype scattered in the clustering trees,without specific correlation with PFGE subtypes.4 out of 5 strains,which showed medium-active motility,belonged to one branch,with the similarity coefficient at 80.9％-100.0％ ; while all the toxic genotype belonged to type B.Conclusion Biotype 1A Yersinia enterocolitica has many clones,whose PFGE types had relations with motility but no relations with virulent genotype and host. Key words: Yersinia enterocolitica; Pulsed field gel electrophoresis; Genotype