Salmonella enterica serovar Infantis presents an ever-increasing threat to public health because of its spread throughout many countries and association with high levels of antimicrobial resistance (AMR). We analyzed whole-genome sequences of 5,284 Salmonella Infantis strains from 74 countries, isolated during 1989-2020 from a wide variety of human, animal, and food sources, to compare genetic phylogeny, AMR determinants, and plasmid presence. The global Salmonella Infantis population structure diverged into 3 clusters: a North American cluster, a European cluster, and a global cluster. The levels of AMR varied by Salmonella Infantis cluster and by isolation source; 73% of poultry isolates were multidrug resistant, compared with 35% of human isolates. This finding correlated with the presence of the pESI megaplasmid; 71% of poultry isolates contained pESI, compared with 32% of human isolates. This study provides key information for public health teams engaged in reducing the spread of this pathogen.

婴儿肠道血清型沙门氏菌由于在许多国家传播且与高水平的抗菌素耐药性 (AMR) 相关，对公众健康构成越来越大的威胁。我们分析了来自 74 个国家的 5,284 个婴儿沙门氏菌菌株的全基因组序列，这些菌株是在 1989 年至 2020 年期间从各种人类、动物和食物来源中分离出来的，以比较遗传系统发育、AMR 决定因素和质粒存在。全球婴儿沙门氏菌种群结构分为 3 个集群：北美集群、欧洲集群和全球集群。AMR 水平因婴儿沙门氏菌群和分离来源而异；73% 的家禽分离株具有多重耐药性，而人类分离株的这一比例为 35%。这一发现与 pESI 巨质粒的存在相关；71% 的家禽分离株含有 pESI，而人类分离株的这一比例为 32%。这项研究为致力于减少这种病原体传播的公共卫生团队提供了关键信息。