Streptococcus suis sequence type 7 outbreak, Sichuan, China.
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.
Ye
Changyun
C
State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Changping, Beijing 102206, People's Republic of China.
Zhu
Xiaoping
X
Jing
Huaiqi
H
Du
Huamao
H
Segura
Mariela
M
Zheng
Han
H
Kan
Biao
B
Wang
Lili
L
Bai
Xuemei
X
Zhou
Yongyun
Y
Cui
Zhigang
Z
Zhang
Shouying
S
Jin
Dong
D
Sun
Na
N
Luo
Xia
X
Zhang
Ji
J
Gong
Zhaolong
Z
Wang
Xin
X
Wang
Lei
L
Sun
Hui
H
Li
Zhenjun
Z
Sun
Qiangzheng
Q
Liu
Honglu
H
Dong
Boqing
B
Ke
Changwen
C
Yuan
Hui
H
Wang
Hua
H
Tian
Kecheng
K
Wang
Yu
Y
Gottschalk
Marcelo
M
Xu
Jianguo
J
D000818:Animals; D002681:China / Q000453:epidemiology; D004269:DNA, Bacterial / Q000032:analysis; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D017011:Streptococcus suis / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D013552:Swine / Q000382:microbiology; D013553:Swine Diseases / Q000453:epidemiology* / Q000382:microbiology; D014774:Virulence
D004269:DNA, Bacterial