Abstract：
Salmonella enterica serovar Typhimurium is an important foodborne pathogen associated with human salmonellosis worldwide. A retrospective screening was performed to elucidate the prevalence, antimicrobial resistance, and phylogenomic characterization of this pathogen in Shanghai, China. S. Typhimurium isolates were selected from 2,211 serotyped Salmonella isolates collected during 2007-2019. Two hundred and seventy-seven S. Typhimurium isolates were detected in 15 of 16 districts in Shanghai. It was noted that 214 (77.3%) isolates were multi-drug resistant and 32 (11.6%) isolates were resistant to ciprofloxacin and 5 (1.8%) isolates were further resistant to ceftriaxone. Poisson generalized linear mixed model results showed that the multi-drug resistance (MDR) in 2017 and 2018 was significantly higher than that in 2010 (P＜0.05), highlighting an increase in the risk of MDR. Phylogenetic results showed that a global data set of 401 sequenced S. Typhimurium isolates was classified into four clones (ST36, ST313, ST19, and ST34), which appeared in international clonal dissemination. The ST34 isolates from China fell into two clades, ST34C1 and ST34C2, the latter of which might originate from Shanghai, and then expanded nationally, accompanied by extended-spectrum β-lactamase gene blaCTX-M-14 and a mutation in quinolone resistance-determining region of the gyrA 87 site. Furthermore, blaCTX-M-14 linking to ISEcp1 upstream and ΔIS903B downstream was found in IncI (Gamma)-like plasmids, and the plasmid conjugation contributed to its horizontal transmission. To our knowledge, it is the first report of the epidemiological and phylogenetic characterization for S. Typhimurium including the emerged clade ST34C2 in Shanghai, warranting the necessity of surveillance for this high-risk pathogen.
OBJECTIVE: Our study uncovered a widespread distribution of Salmonella enterica serovar Typhimurium isolates in Shanghai accompanied by the increase in antimicrobial resistance (AMR) especially MDR during a 10-year period, which filled in the gap about a long period of continuous monitoring of AMR in this pathogen in Shanghai. Meanwhile, we identified a new clade ST34C2 of S. Typhimurium with the acquisition of IncI (Gamma)-like plasmids mediated by extended-spectrum β-lactamase gene blaCTX-M-14 as well as gyrA 87 mutation, which had not been reported before. It was noted that IncI (Gamma)-like plasmids were reported in S. Typhimurium for the first time and conjugation could accelerate the spread of antimicrobial resistance gene blaCTX-M-14. These findings on the epidemic, antimicrobial resistance, and phylogenomic characterization for S. Typhimurium provide valuable insights into its potential risk to public health and also the basis for AMR prevention and control strategies in Shanghai in the future.
OBJECTIVE: Our study uncovered a widespread distribution of Salmonella enterica serovar Typhimurium isolates in Shanghai accompanied by the increase in antimicrobial resistance (AMR) especially MDR during a 10-year period, which filled in the gap about a long period of continuous monitoring of AMR in this pathogen in Shanghai. Meanwhile, we identified a new clade ST34C2 of S. Typhimurium with the acquisition of IncI (Gamma)-like plasmids mediated by extended-spectrum β-lactamase gene blaCTX-M-14 as well as gyrA 87 mutation, which had not been reported before. It was noted that IncI (Gamma)-like plasmids were reported in S. Typhimurium for the first time and conjugation could accelerate the spread of antimicrobial resistance gene blaCTX-M-14. These findings on the epidemic, antimicrobial resistance, and phylogenomic characterization for S. Typhimurium provide valuable insights into its potential risk to public health and also the basis for AMR prevention and control strategies in Shanghai in the future.
摘要：
肠沙门氏菌是世界范围内与人类沙门氏菌病相关的重要食源性病原体。进行了回顾性筛查以阐明患病率，抗菌素耐药性，和该病原体在上海的系统发育特征，中国。鼠伤寒沙门氏菌分离株是从2007-2019年收集的2,211株血清分型沙门氏菌分离株中选择的。在上海16个地区中的15个地区检测到二百七十七株鼠伤寒沙门氏菌。值得注意的是，214（77.3％）个分离株对多种药物耐药，32（11.6％）个分离株对环丙沙星耐药，5（1.8％）个分离株对头孢曲松进一步耐药。Poisson广义线性混合模型结果显示,2017年和2018年的多药耐药性(MDR)明显高于2010年(P＜0.05),强调MDR风险的增加。系统发育结果表明，401个测序的鼠伤寒沙门氏菌分离株的全球数据集被分为四个克隆（ST36，ST313，ST19和ST34），出现在国际克隆传播中。来自中国的ST34分离株分为两个分支，ST34C1和ST34C2，后者可能来自上海，然后在全国范围内扩张，伴有超广谱β-内酰胺酶基因blaCTX-M-14和gyrA87位点喹诺酮耐药决定区的突变。此外，在InCI（Gamma）样质粒中发现了blaCTX-M-14与ISECp1上游和ΔIS903B下游连接，质粒接合有助于其水平传播。据我们所知,这是鼠伤寒沙门氏菌的流行病学和系统发育特征的第一份报告，包括在上海出现的进化枝ST34C2，保证对这种高风险病原体进行监测的必要性。
目的：我们的研究发现，在10年期间，上海广泛分布的肠道沙门菌血清型鼠伤寒沙门氏菌菌株伴随着抗菌药物耐药性（AMR）尤其是MDR的增加。填补了上海市长期持续监测该病原体AMR的空白。同时,我们鉴定了一种新的鼠伤寒沙门氏菌进化枝ST34C2，获得了由广谱β-内酰胺酶基因blaCTX-M-14以及gyrA87突变介导的IncI（γ）样质粒，以前没有报道过。值得注意的是，IncI（Gamma）样质粒首次在鼠伤寒沙门氏菌中报道，结合可以加速抗微生物抗性基因blaCTX-M-14的传播。这些关于流行病的发现，抗菌素耐药性，以及鼠伤寒沙门氏菌的系统基因组特征为其对公众健康的潜在风险提供了有价值的见解，也是未来上海AMR预防和控制策略的基础。
目的：我们的研究发现，在10年期间，上海广泛分布的肠道沙门菌血清型鼠伤寒沙门氏菌菌株伴随着抗菌药物耐药性（AMR）尤其是MDR的增加。填补了上海市长期持续监测该病原体AMR的空白。同时,我们鉴定了一种新的鼠伤寒沙门氏菌进化枝ST34C2，获得了由广谱β-内酰胺酶基因blaCTX-M-14以及gyrA87突变介导的IncI（γ）样质粒，以前没有报道过。值得注意的是，IncI（Gamma）样质粒首次在鼠伤寒沙门氏菌中报道，结合可以加速抗微生物抗性基因blaCTX-M-14的传播。这些关于流行病的发现，抗菌素耐药性，以及鼠伤寒沙门氏菌的系统基因组特征为其对公众健康的潜在风险提供了有价值的见解，也是未来上海AMR预防和控制策略的基础。
