ABSTRACT
Objective To develop a PFGE protocol for Streptococcus suis.Methods We developed and optimized a PFGE protocol for S.suis,in terms of plug preparation,choice of restriction endonucleases and optimized electrophoresis parameters.By analyzing the genome sequences of S.suis P1/7 with Mapdraw of DNAStar.we found three restriction enzymes,Swa Ⅰ,Sma Ⅰ and Apa Ⅰ,were more suitable than others.Results Analysis of 100 isolates of S.suis including 34 of 35 serotypes identified,59,53 and 43 patterns were obtained from Swa Ⅰ,Sma Ⅰ and Apa Ⅰ restriction,respectively.The enzyme Swa Ⅰ had the greatest power for discrimination ability.Conclusion By optimization of the protocol at various conditions,a rapid,reproducible,economic and practical PFGE method for S.suis was developed.
ABSTRACT
<p><b>OBJECTIVE</b>In mid-July 2005, five patients presented with septic shock to a hospital in Ziyang city in Sichuan, China, to identify the etiology of the unknown reason disease, an epidemiological, clinical, and laboratory study were conducted.</p><p><b>METHODS</b>An enhanced surveillance program were established in Sichuan, the following activities were introduced: active case finding in Sichuan of (a) laboratory diagnosed Streptococcus suis infection and (b) clinically diagnosed probable cases with exposure history; supplemented by (c) monitoring reports on meningococcal meningitis. Streptococcus suis serotype 2 infection was confirmed by culture and biochemical reactions, followed by sequencing for specific genes for serotype and virulence factors.</p><p><b>RESULTS</b>From June 10 to August 21, 2005, 68 laboratory confirmed cases of human Streptococcus suis infections were reported. All were villagers who gave a history of direct exposure to deceased or sick pigs in their backyards where slaughtering was performed. Twenty six (38%) presented with toxic shock syndrome of which 15 (58%) died. Other presentations were septicaemia or meningitis. All isolates were tested positive for genes for tuf, species-specific 16S rRNA, cps2J, mrp, ef and sly. There were 136 clinically diagnosed probable cases with similar exposure history but incomplete laboratory investigations.</p><p><b>CONCLUSION</b>An outbreak of human Streptococcus suis serotype 2 infections occurred in villagers after direct exposure to deceased or sick pigs in Sichuan. Prohibition of slaughtering in backyards brought the outbreak to a halt. A virulent strain of the bacteria is speculated to be in circulation, and is responsible for the unusual presentation of toxic shock syndrome with high case fatality.</p>