Streptococcus suis outbreak investigation using multiple-locus variable tandem repeat number analysis.
Two outbreaks of Streptococcus suis ST7 occurred in humans in 1998 and 2005 in China. PFGE of chromosome restriction fragments found all ST7 isolates to be indistinguishable. Due to the genetic homogeneity of ST7 isolates, development of a rapid sub-typing method with high discriminatory power for ST7 isolates is required. In this study, a novel method, MLVA, was developed to type S. suis serotype 2 strains. Further, this method was used to analyze outbreak-associated ST7 strains in China. A total of 144 ST7 S. suis isolates were sub-typed into 34 MLVA types. Among these, eight isolates from the 1998 outbreak were sub-typed into five MLVA types, of which four MLVA types were also detected in Sichuan in 2005. These data indicate that the pathogens responsible for the two outbreaks had the same origin. In addition, some observations also provided molecular evidence for the transmission route, possibly indicating that the MLVA method has usefulness in epidemiology. The developed MLVA scheme for S. suis has greater discriminative power than PFGE. The method described here may be useful for identifying the source of S. suis infection and monitoring its spread.
Li
Wei
W
State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.
Ye
Changyun
C
Jing
Huaiqi
H
Cui
Zhigang
Z
Bai
Xuemei
X
Jin
Dong
D
Zheng
Han
H
Zhao
Ailan
A
Xu
Yanmei
Y
Gottschalk
Marcelo
M
Xu
Jianguo
J
D000818:Animals; D015373:Bacterial Typing Techniques / Q000379:methods*; D002170:Canada / Q000453:epidemiology; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005060:Europe / Q000453:epidemiology; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary*; D017011:Streptococcus suis / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D013552:Swine; D013553:Swine Diseases / Q000453:epidemiology / Q000382:microbiology*; D020080:Tandem Repeat Sequences