Emerging Infectious Diseases (Aug 2006)

Streptococcus suis Sequence Type 7 Outbreak, Sichuan, China

  • Changyun Ye,
  • Xiaoping Zhu,
  • Huaiqi Jing,
  • Huamao Du,
  • Mariela Segura,
  • Han Zheng,
  • Biao Kan,
  • Lili Wang,
  • Xuemei Bai,
  • Yongyun Zhou,
  • Zhigang Cui,
  • Shouying Zhang,
  • Dong Jin,
  • Na Sun,
  • Xia Luo,
  • Ji Zhang,
  • Zhaolong Gong,
  • Xin Wang,
  • Lei Wang,
  • Hui Sun,
  • Zhenjun Li,
  • Qiangzheng Sun,
  • Honglu Liu,
  • Boqing Dong,
  • Changwen Ke,
  • Hui Yuan,
  • Hua Wang,
  • Kecheng Tian,
  • Yu Wang,
  • Marcelo Gottschalk,
  • Jianguo Xu

DOI
https://doi.org/10.3201/eid1208.060232
Journal volume & issue
Vol. 12, no. 8
pp. 1203 – 1208

Abstract

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An outbreak of Streptococcus suis serotype 2 emerged in the summer of 2005 in Sichuan Province, and sporadic infections occurred in 4 additional provinces of China. In total, 99 S. suis strains were isolated and analyzed in this study: 88 isolates from human patients and 11 from diseased pigs. We defined 98 of 99 isolates as pulse type I by using pulsed-field gel electrophoresis analysis of SmaI-digested chromosomal DNA. Furthermore, multilocus sequence typing classified 97 of 98 members of the pulse type I in the same sequence type (ST), ST-7. Isolates of ST-7 were more toxic to peripheral blood mononuclear cells than ST-1 strains. S. suis ST-7, the causative agent, was a single-locus variant of ST-1 with increased virulence. These findings strongly suggest that ST-7 is an emerging, highly virulent S. suis clone that caused the largest S. suis outbreak ever described.

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