Table_1_The Current Landscape of Antibiotic Resistance of Salmonella Infantis in Italy: The Expansion of Extended-Spectrum Beta-Lactamase Producers on a Local Scale.XLSX

Salmonella enterica serovar Infantis is one of the five main causes of human salmonellosis in the European Union (EU) and in recent years, has been increasingly reported to carry multiple antimicrobial resistance determinants, including extended-spectrum beta-lactamase (ESBL) genes. In our study, we used WGS-based tools to characterize S. Infantis strains circulating in the Abruzzo and Molise regions of Italy between 2017 and 2020 and compared this local dataset to the S. Infantis population present in Italy over the last two decades. Phylogenetic analyses demonstrated that the majority of strains isolated from poultry and turkeys from Abruzzo and Molise were closely related and belonged to one of the two main genetic clusters present in Italy, which were grouped predominantly as ESBL-producing strains that harbored pESI-like plasmid. We showed that 60% of the local strains carried multiple antibiotic resistance genes, including ESBL gene blaCTX–M–1 as well as aadA1, dfrA1, dfrA14, sul1, and tet(A) genes present on the pESI-like megaplasmid. The analysis of strains from Abruzzo and Molise and the publicly available Italian S. Infantis sequences revealed a dramatic increase in the number of identified AMR genes in the strains isolated after 2011. Moreover, the number of strains resistant to five or more antibiotic classes increased from 20–80% in the last decade likely due to the acquisition of the megaplasmid. The persistence of the ESBL-producing and the multidrug-resistant (MDR) clone of S. Infantis in poultry populations in Italy and in Europe requires rapid and efficient intervention strategies to prevent further expansion of the clone.

肠炎沙门菌Infantis血清型（Salmonella enterica serovar Infantis）是欧盟（EU）范围内引发人类沙门氏菌病的五大主要致病菌之一，近年来，该菌携带多重抗菌耐药决定因子的报道逐渐增多，其中涵盖超广谱β-内酰胺酶（extended-spectrum beta-lactamase, ESBL）基因。本研究借助基于全基因组测序（Whole Genome Sequencing, WGS）的分析工具，对2017至2020年间在意大利阿布鲁佐与莫利塞地区流行的S. Infantis菌株进行分型鉴定，并将该本地数据集与近二十年间意大利境内的S. Infantis种群进行对比分析。系统发育分析结果表明，从阿布鲁佐和莫利塞地区家禽及火鸡样本中分离得到的绝大多数菌株亲缘关系紧密，且隶属于意大利境内存在的两大主要遗传簇之一，该遗传簇主要由携带类pESI质粒的产ESBL菌株构成。本研究证实，60%的本地菌株携带多种抗生素耐药基因，包括位于类pESI大质粒上的ESBL基因blaCTX-M-1，以及aadA1、dfrA1、dfrA14、sul1和tet(A)耐药基因。对阿布鲁佐和莫利塞地区菌株以及公开可用的意大利S. Infantis序列开展的分析显示，2011年后分离的菌株中，鉴定到的抗菌药物耐药（antimicrobial resistance, AMR）基因数量显著上升。此外，对五类及以上抗生素类别耐药的菌株占比在过去十年间从20%升至80%，这一变化大概率与该菌株获得类pESI大质粒相关。意大利乃至欧洲家禽种群中产ESBL的多重耐药（multidrug-resistant, MDR）S. Infantis克隆株的持续存在，提示亟需制定快速高效的干预策略，以阻止该克隆株的进一步扩散。