ST6型金黄色葡萄球菌食物中毒菌株的毒力因子分析

目的检测食物中毒优势型ST6型菌株的毒力基因特征,为食品安全风险评估、食源性病原菌的监测和致病性研究提供依据。方法选取深圳地区7次食物中毒收集的32株ST6型菌株进行全基因组测序,利用VFDB数据库进行毒力因子分析,并通过序列比对进行SEA亚型分析。结果第1-4起食物中毒ST6菌株携带的毒力因子谱完全相同;第5-7起食物中毒中,同一起食物中毒的暴发菌株携带的毒力因子一致,而非暴发菌株与暴发菌株携带的毒力因子不完全一致。在32株ST6型菌中,与粘附、酶和Ⅶ型分泌系统相关的毒力基因具有较高的携带率,α-溶血素(hly/hla)、β-溶血素(hlb)、δ-溶血素(hld)、γ-溶血素基因(hlgA、hlgB、hlgC)、肠毒素A基因(sea)和表皮剥脱毒素A基因(eta)的携带率均为100%,双组分白细胞毒素LukDE基因(lukD和lukE)的携带率为96.8%。所有菌株携带的肠毒素A均为SEA1亚型。结论32株ST6型食物中毒相关菌株携带多个毒力因子基因,以cna、sea、eta、lukD、lukE毒力基因携带率较高,编码的毒力因子可能对ST6型菌株的致病性产生影响。

Virulence factors of sequence type(ST)6 Staphylococcus aureus in food poisoning outbreaks

Objective To determine the characteristics of the virulence genes of the dominant Staphylococcus aureus sequence type(ST)6 strains causing food poisoning in order to provide a basis for risk assessment of food safety,monitoring of foodborne pathogens,and research on pathogenicity.Methods Thirty-two S.aureus ST6 strains from 7 food poisoning outbreaks in Shenzhen were selected for whole-genome sequencing,virulence factors were analyzed using the VFDB database,and SEA subtype analysis was performed using sequence alignment.Results The virulence factors profiles of S.aureus ST6 strains from food poisoning outbreaks 1 to 4 were identical.The virulence factors of strains causing outbreaks 5 to 7 matched,but the virulence factors of strains not causing outbreaks and those causing outbreaks differed.Virulence factors associated with adhesion,enzymes,and a typeⅦsecretion system were highly prevalent among the 32 S.aureus ST6 strains.The prevalence ofα-hemolysin genes(hly/hla),aβ-hemolysin gene(hlb),aδ-hemolysin gene(hld),γ-hemolysin genes(hlgA,hlgB,hlgC),an enterotoxin A gene(sea),and an epidermal detoxification toxin A gene(eta)was 100%,and the prevalence of two component leukotoxin LukDE genes(lukD and lukE)was 96.8%.The enterotoxin SEA1 subtype was identified in all strains.Conclusion The 32 S.aureus ST6 strains causing food poisoning carried multiple virulence factors.cna,sea,eta,lukD,and lukE were relatively prevalent.This may affect the pathogenicity of S.aureus ST6 strains.