High carriage and possible hidden spread of multidrug-resistant Salmonella among asymptomatic workers in Yulin, China

We investigated Salmonella carriage among food workers compared with non-food workers based on occupational health screening of 260,315 asymptomatic workers over an 8-year surveillance period in Yulin, China. We confirmed that healthy carriers serve as natural reservoirs for Salmonella, with higher carriage rates in food workers than non-food workers. The isolates from food workers also exhibited greater serovar diversity and likely higher levels of antimicrobial resistance than those from non-food workers. Factors such as meteorological, social, and hygiene factors potentially influenced the carriage rate. Genomic analysis revealed a consistent increase in antimicrobial resistance genes among Salmonella isolates over the study period, with the majority of these antimicrobial resistance genes located on plasmids. Additionally, we identified numerous closely related bacterial clusters, which might reflect clusters of hidden local foodborne infections.

本研究基于中国榆林市为期8年的监测周期内260315名无症状劳动者的职业健康筛查数据，对比分析了食品从业人员与非食品从业人员的沙门氏菌（Salmonella）带菌状态。研究证实，健康带菌者为沙门氏菌的天然储存宿主，且食品从业人员的带菌率显著高于非食品从业人员。从食品从业人员体内分离得到的沙门氏菌，其血清型多样性及抗菌药物耐药水平均高于非食品从业人员的分离菌株。气象、社会及卫生等多类因素，可能对沙门氏菌带菌率产生影响。基因组分析结果显示，在整个研究周期内，沙门氏菌分离株携带的抗菌药物耐药基因数量呈持续上升趋势，且此类耐药基因大多位于质粒上。此外，本研究还发现了大量高度同源的细菌聚类簇，这或许反映出当地存在未被发现的食源性感染聚集性事件。