我国食源性金黄色葡萄球菌耐药及遗传特征情况研究

Resistance and genotype characterization of foodborne Staphylococcus aureus in China

目的探究我国2020年食源性金黄色葡萄球菌的耐药性、毒力因子及分子分型特征。方法采用微量肉汤稀释法对菌株进行药物敏感性试验,基于全基因序列分析多位点序列分型及重要耐药基因(mecA)和毒力基因。结果224株食源性金黄色葡萄球菌对12类抗菌药物的整体耐药率为87.9%(197/224),对青霉素的耐药率最高为82.6%(185/224)。多重耐药率为23.2%(52/224),多重耐药菌中ST398占比最高为26.9%(14/52),耐甲氧西林金黄色葡萄球菌检出率为8.0%(18/224)。葡萄球菌肠毒素基因整体携带率为52.2%(117/224),其中sea的携带率最高为24.6%(55/224),携带肠毒素基因种类最多的ST型为ST1。共检测到31种ST型,其中ST7最多(12.9%,29/224),ST398次之(10.7%,24/224)。中毒性休克综合征毒素编码基因(tsst-1)和杀白细胞素编码基因(lukF-PV和lukS-PV)的携带率分别为6.3%(14/224)和4.5%(10/224)。结论我国食源性金黄色葡萄球菌耐药率和肠毒素携带率均较高,且检出了临床感染中重要的毒力基因,提示食品中金黄色葡萄球菌的潜在危害不容忽视。ST型与食品类别、耐药性和致病性存在一定相关性,可为了解我国食源性金黄色葡萄球菌的流行特征和风险防控提供数据支撑。

Objective To explore the characteristics of resistance,virulence factor and sequence typing of foodborne Staphylococcus aureus(S.aureus)in China in 2020.Methods Antimicrobial susceptibility test for S.aureus was performed using the broth microdilution method.Multilocus sequence typing(MLST),the important antibiotic resistance gene mecA,and virulence genes were analyzed using whole genome sequencing.Results The overall resistance rate of the 224 foodborne S.aureus isolates to 12 classes of antimicrobials was 87.9%(197/224),with the highest resistance rate of 82.6%(185/224)to penicillin.The multi-drug resistance rate was 23.2%(52/224),with ST398 accounting for the highest percentage(26.9%,14/52)of multi-drug resistant bacteria.The methicillin-resistant S.aureus detection rate was 8.0%(18/224).The overall carriage rate of staphylococcal enterotoxin genes was 52.2%(117/224),with sea having the highest carriage rate of 24.6%(55/224).The ST type of S.aureus carrying the most types of enterotoxin genes was ST1.A total of 31 ST types were detected in this study,among which ST7(12.9%,29/224)was the predominant ST of isolates,followed by ST398(10.7%,24/224).In addition,the carriage rates of toxic shock syndrome toxin coding gene(tsst-1)and leukocytocin encoding genes(lukF-PV and lukS-PV)were 6.3%(14/224)and 4.5%(10/224),respectively.Conclusion The high rate of antimicrobial resistance and enterotoxin genes carriage of foodborne S.aureus in China and the detection of virulence genes that play an important role in clinical infection suggest that the potential hazards of S.aureus in food should not be ignored.There is a high correlation between ST type and food type,antimicrobial susceptibility,and pathogenicity,which provides scientific data for further analysis of the epidemiological characteristics and risk prevention and control of foodborne S.aureus in China.