Analysis of Relationships between Several Shigella sonnei Outbreaks in the Taoyuan Area of Taiwan
2001 Vol.17 NO.4
In the period between November 1995 and January 1996, there was a large-scale Shigella sonnei outbreak in the Taoyuan area. During the period between October 1998 and February 1999 in the same area, there were again five S. sonnei outbreaks. To understand the relationships between these outbreaks a study of the typing of the microbe was conducted using antimicrobial susceptibility testing, plasmid profile analysis, and pulsed-field gel electrophoresis (PFGE) methods. During the six outbreaks, a total of 55 S. sonnei isolates were collected. By antimicrobial susceptibility testing, these isolates were grouped into two types; by plasmid profile analysis, they were classified into three types; the PFGE method demonstrated only one type. The finding and the locality and timing of these outbreaks suggested that the S. sonnei isolates of the six outbreaks were closely related. It was therefore decided that the S. sonnei strains isolated in the period 1998-1999 and the strains isolated during the 1995 large-scale outbreak had, a molecular-epidemiological and genetic clonal relationship.