目的 探讨不同来源的鼠伤寒沙门菌侵袭力和毒力基因表达的差异.方法 从腹泻患者粪便、河水及土壤中共分离出鼠伤寒沙门菌(分别简称为临床株、水体株、土壤株)34株,分析菌株在上皮细胞黏附、侵袭以及巨噬细胞内复制能力的差异;选择与黏附、侵袭以及复制阶段相关的毒力基因(鞭毛合成位点filC,致病岛1位点hilA、invI,致病岛2位点ssrA、sseF),通过实时荧光定量聚合酶链反应(PCR)检测不同来源细菌的毒力基因表达差异.结果 土壤株和水体株的黏附力和侵袭力与标准菌株(ATCC 14028)类似,但80%左右的临床株表现出比标准菌株(ATCC 14028)更高的黏附力和侵袭力.在巨噬细胞内的复制结果 显示,临床株、土壤株以及水体株的胞内复制能力均与标准菌株(ATCC 14028)类似.不同菌株的毒力基因表达情况与细胞黏附、侵袭及胞内复制结果 相吻合.高侵袭力临床株在黏附期filC基因以及侵袭期hilA、invI基因的表达量显著高于标准菌株(ATCC 14028)(P<0.05),而胞内复制期ssrA和sseF基因的表达量与标准菌株(ATCC 14028)类似.土壤株和水体株在不同时期的基因表达量均与标准菌株(ATCC 14028)类似.结论 鼠伤寒沙门菌临床株显示出较环境菌株更强的黏附力、侵袭力及更多的相应毒力基因表达量,应着重加强对医院内沙门菌感染的防控措施,降低医源性沙门菌的感染率.%Objective To analyze the difference of invasion abilities and the virulence gene expressions of Salmonella typhimurium with different origins. Methods A total of 34 isolates of Salmonella typhimurium were collected from soil(strains from soil),water(strains from water) and patients with diarrhea(clinical strains),and their abilities of attachment and invasion to epithelial cells and abilities of replication in macrophages were compared. Real-time fluorescence quantitation polymerase chain reaction(PCR) was used to determine the virulence gene expressions of Salmonella typhimurium with different origins. The virulence genes,including flagella locus filC,Salmonella pathogenicity island-1 loci hilA and invI,and Salmonella pathogenicity island-2 loci ssrA and sseF,were determined. Results The attachment and invasion abilities of strains from soil and water were comparable to those of standard strain(ATCC 14028),while about 80% clinical strains exhibited higher attachment and invasion abilities to epithelial cells. Macrophage replication assay showed that all the strains showed comparable replication ability with that of standard strain(ATCC 14028). The expression patterns of virulence genes in different strains were highly consistent with the results of the attachment and invasion abilities and the replication abilities in macrophages. In line with the results of invasion ability,clinical strains showed high filC,hilA and invI gene expressions relative to that of standard strain(ATCC 14028)(P<0.05),while the gene expressions of ssrA and sseF were not altered. Strains from soil and water showed comparable expression of all the determined genes to that of standard strain(ATCC 14028).Conclusions Clinical strains exhibit higher invasion ability and virulence gene expression than those of environmental strains,and the controlling for clinical strains should be highlighted to prevent from nosocomial infection. Abstract:Objective To analyze the difference of invasion abilities and the virulence gene expressions of Salmonella typhimurium with different origins.Methods A total of 34 isolates of Salmonella typhimurium were collected from soil(strains from soil),water(strains from water) and patients with diarrhea(clinical strains),and their abilities of attachment and invasion to epithelial cells and abilities of replication in macrophages were compared. Real-time fluorescence quantitation polymerase chain reaction(PCR) was used to determine the virulence gene expressions of Salmonella typhimurium with different origins. The virulence genes,including flagella locus filC,Salmonella pathogenicity island-1 loci hilA and invI,and Salmonella pathogenicity island-2 loci ssrA and sseF,were determined. Results The attachment and invasion abilities of strains from soil and water were comparable to those of standard strain(ATCC 14028),while about 80% clinical strains exhibited higher attachment and invasion abilities to epithelial cells. Macrophage replication assay showed that all the strains showed comparable replication ability with that of standard strain(ATCC 14028). The expression patterns of virulence genes in different strains were highly consistent with the results of the attachment and invasion abilities and the replication abilities in macrophages. In line with the results of invasion ability,clinical strains showed high filC,hilA and invI gene expressions relative to that of standard strain(ATCC 14028)(P<0.05),while the gene expressions of ssrA and sseF were not altered. Strains from soil and water showed comparable expression of all the determined genes to that of standard strain(ATCC 14028). Conclusions Clinical strains exhibit higher invasion ability and virulence gene expression than those of environmental strains,and the controlling for clinical strains should be highlighted to prevent from nosocomial infection.
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