Bernaquez Isabelle, Dumaresq Jeannot, Picard Isabelle, Gaulin Colette, Dion Réjean, Weaver Kim, Walker Matthew, Kearney Ashley, Bharat Amrita, Fafard Judith, Bekal Sadjia
Laboratoire de santé publique du Québec (LSPQ), Institut national de santé publique du Québec (INSPQ), Sainte-Anne-de-Bellevue, Canada.
Département de microbiologie, infectiologie et immunologie, Faculté de Médecine, Université de Montréal, Montréal, Canada.
Commun Med (Lond). 2025 Jun 4;5(1):214. doi: 10.1038/s43856-025-00919-2.
Salmonella enterica serovar 4,[5],12:i:- (S. 4,[5],12:i:-), the monophasic variant of Typhimurium, is among the most prevalent surface antigen subtypes and most frequent carriers of multidrug-resistance in Salmonella worldwide, therefore becoming a prominent public health threat.
Genomic surveillance data analysis, in addition to human case and animal health investigations and food inspections from Quebec, Canada were conducted to identify the source of an emerging S. 4,[5],12:i:- cluster from 2021-2023. We performed antimicrobial susceptibility testing, whole genome sequencing, phylogeny and comparative genomic analyses to characterize this local strain.
We show that a cluster of 41 S. 4,[5],12:i:- emerged in Quebec, Canada, after acquiring a self-conjugative IncHI2A plasmid encoding extensive drug-resistance (mph(A), bla, qnrS1) and potential reduced biocide susceptibility via efflux pump regulators (ramAp, marR), metal resistance (terZABCDE, copG) and oxidative stress responses (umuDC, dsbC), among other mechanisms. Genomic epidemiology identifies 20 human cases, 16 veal calves, 3 dogs, one piglet, one moose, and 4 raw meat-based diet isolates belonging to this cluster. Infants are mainly (50%) affected, and dogs fed raw meat-based diets are the major source identified, followed by exposure to cattle. Retrospective genomic analyses demonstrates its association to USA porcine and shared plasmid pool among many food-producing animals, but indicated different niches for different plasmid subtypes.
This study highlights the threat of S. 4,[5],12:i:- ST34 and its raw pet food-based transmission to vulnerable human populations, where impacted veal farms and asymptomatic dogs can act as disease carriers with limited treatment options and possible environmental persistence.
肠炎沙门氏菌血清型4,[5],12:i:-（鼠伤寒沙门氏菌单相变体）是全球沙门氏菌中最普遍的表面抗原亚型之一，也是多重耐药性最常见的携带者，因此成为一个突出的公共卫生威胁。
除了对加拿大魁北克省的人类病例、动物健康调查和食品检查进行基因组监测数据分析外，还开展这些工作以确定2021年至2023年出现的4,[5],12:i:-集群的来源。我们进行了抗菌药物敏感性测试、全基因组测序、系统发育和比较基因组分析，以表征这种本地菌株。
我们发现，在获得一个自我接合的IncHI2A质粒后，加拿大魁北克省出现了一个由41株4,[5],12:i:-组成的集群，该质粒编码广泛耐药性（mph(A)、bla、qnrS1），并通过外排泵调节因子（ramAp、marR）、金属抗性（terZABCDE、copG）和氧化应激反应（umuDC、dsbC）等机制可能降低对杀菌剂的敏感性。基因组流行病学确定了属于该集群的20例人类病例、16头犊牛、3只狗、1头仔猪、1头驼鹿和4株基于生肉饮食的分离株。主要受影响的是婴儿（50%），以生肉为食的狗是确定的主要来源，其次是接触牛。回顾性基因组分析表明，它与美国猪以及许多食用动物之间共享的质粒库有关，但表明不同的质粒亚型存在不同的生态位。
本研究强调了4,[5],12:i:- ST34及其基于生的宠物食品传播对脆弱人群的威胁，其中受影响的犊牛养殖场和无症状的狗可能成为疾病携带者，治疗选择有限且可能在环境中持续存在。
