Posgrado en Microbiología, Centro de Investigaciones Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico.
Departament of Microbiology and Environmental Toxicology, University of California at Santa Cruz, Santa Cruz, CA, United States.
Front Cell Infect Microbiol. 2023 Oct 9;13:1237725. doi: 10.3389/fcimb.2023.1237725. eCollection 2023.
Food contamination with pathogenic can cause severe disease. Here, we report the isolation of a multidrug resistant strain (A23EC) from fresh spinach. A23EC belongs to subclade C2 of ST131, a virulent clone of Extraintestinal Pathogenic (ExPEC). Most A23EC virulence factors are concentrated in three pathogenicity islands. These include PapGII, a fimbrial tip adhesin linked to increased virulence, and and , two adhesins known to facilitate spinach leaf colonization. A23EC also bears Tn, a chromosomally-integrated transposon with the demonstrated potential to facilitate the evolution of carbapenem resistance among non-carbapenemase-producing enterobacterales. This transposon consists of two IS-bound modular translocatable units (TUs). The first TU carries , , , , and , and the second one harbors . A23EC also bears a self-transmissible plasmid that can mediate conjugation at 20°C and that has a mosaic IncF [F(31,36):A(4,20):B1] and Col156 origin of replication. Comparing A23EC to 86 additional complete ST131 sequences, A23EC forms a monophyletic cluster with 17 other strains that share the following four genomic traits: (1) virotype E (+); (2) presence of a PAI II-like pathogenicity island with an additional gene; (3) presence of chromosomal Tn; and (4) frequent presence of an F(31,36):A(4,20):B1 plasmid. Sequences belonging to this cluster (which we named "C2b sublineage") are highly enriched in septicemia samples and their associated genetic markers align with recent reports of an emerging, virulent sublineage of the C2 subclade, suggesting significant pathogenic potential. This is the first report of a ST131 strain belonging to subclade C2 contaminating green leafy vegetables. The detection of this uropathogenic clone in fresh food is alarming. This work suggests that ST131 continues to evolve, gaining selective advantages and new routes of transmission. This highlights the pressing need for rigorous epidemiological surveillance of ExPEC in vegetables with One Health perspective.
食源性致病菌污染可导致严重疾病。本研究从新鲜菠菜中分离出一株多药耐药菌株（A23EC）。A23EC 属于 ST131 亚组 C2，是肠外致病性大肠杆菌（ExPEC）的一种毒力克隆。大多数 A23EC 毒力因子集中在三个致病性岛中。这些包括与增加毒力相关的纤毛尖端黏附因子 PapGII，以及已知促进菠菜叶定植的黏附因子 和 。A23EC 还携带 Tn，这是一个整合在染色体上的转座子，具有促进非碳青霉烯类产酶肠杆菌科进化为碳青霉烯类耐药的潜力。该转座子由两个 IS 结合的模块化可移动单元（TU）组成。第一个 TU 携带 、 、 、 、 和 ，第二个 TU 则携带 。A23EC 还携带一个自我传播质粒，该质粒可以介导 20°C 下的接合，并且具有镶嵌 IncF [F(31,36):A(4,20):B1] 和 Col156 复制原点。将 A23EC 与 86 个额外的完整 ST131 序列进行比较，A23EC 与 17 株其他菌株形成单系聚类，这些菌株共享以下四个基因组特征：（1）病毒型 E（+）；（2）存在具有额外 基因的 PAI II 样致病性岛；（3）存在染色体 Tn；（4）频繁存在 F(31,36):A(4,20):B1 质粒。属于该聚类的序列（我们称之为“C2b 亚系”）在败血症样本中高度富集，其相关遗传标记与最近关于 C2 亚组新兴毒力亚系的报道一致，表明其具有显著的致病潜力。这是首例污染绿叶蔬菜的 ST131 菌株属于 C2 亚组的报告。在新鲜食品中检测到这种尿路致病性克隆令人警惕。本研究表明，ST131 仍在不断进化，获得选择性优势和新的传播途径。这凸显了从“同一健康”角度对蔬菜中 ExPEC 进行严格的流行病学监测的迫切需要。
