贵阳市甲型副伤寒沙门菌脉冲电场凝胶电泳分型分析

Molecular Typing of Salmonella Paratyphi A Strains from Guiyang of Guizhou Province with Pulsed Field Gel Electrophoresis

目的了解贵阳市甲型副伤寒沙门菌的分子流行病学特征,分析菌株的相似性,为追踪传染来源、查找传播途径提供线索。方法用脉冲电场凝胶电泳(pulsed field gelelectrophoresis,PFGE)方法进行分型。结果根据细菌染色体DNA的SpeI酶切图谱,将贵阳地区146株甲型副伤寒沙门菌分成10个PFGE带型,1型32株占21.9%,2型73株占50.0%,3型13株占8.9%,4型7株占4.8%,5型14株占9.6%,6型、7型、8型和9型各1株,各占0.7%,10型3株占2.7%,各型之间的相似性在98.1%～72.0%。暴发株24株被分为5个PFGE带型,1型占54.2%,带菌者1株为1型。各年菌株的PFGE带型不尽相同,1型和2型为常年流行带型。高流行区县的甲型副伤寒菌株被分为9个PFGE带型。结论贵阳地区甲型副伤寒沙门菌流行复杂以2型和1型为优势流行带型,提示存在同一克隆群的菌株广泛传播。该研究进一步证实PFGE是一种发现或预警暴发的可行服务手段。

Objective To type and group the Salmonella paratyphi A strains isolated in Guiyang from 2000 to 2007 and to understand the epidemiological features caused by the pathogen. Methods Pulsed field gel electrophoresis（PFGE） of large restriction fragments of bacterial chromosomal DNA was applied to type the Salmonella paratyphi A strains. Results Ten PFGE patterns were identified among the 146 S. paratyphi A isolates,where 32 isolates belonged to pattern 1（21.9%）,73 isolates to pattern 2（50.0%）,13 isolates to pattern 3（8.9%）,7 isolates to pattern 4（4.8%）,14 isolates to pattern 5（9.6%）,3 isolates to pattern 10（2.7%） and each of the remaining 3 isolates to an independent pattern（0.7% respectively）. The PFGE type of strains varied year by year,patterns 1 and 2 was domain epidemic patterns; 24 strains from 2 outbreaks had 5 PFGE patterns and the proportion of pattern 1 was 54.2% and the strain isolated from a healthy carrier belonged to pattern 1. Strains isolated from high epidemic areas had 9 PFGE patterns based on the size and number of restriction fragments and patterns which were digested by Spe I. Conclusion The findings of the present study verified the usefulness of PFGE in characterizing and comparing strains of Salmonella Paratyphi A,and forecasting outbreak. The results indicated that although the distribution of PFGE patterns varied among different counties of Guiyang,the pattern 1 and pattern 2 were the epidemic domain,which were responsible for paratyphoid fever in high epidemic counties.