Abstract：
The plasmid of emerging S. Infantis (pESI) or pESI-like plasmid in Salmonella enterica Infantis are consistently reported in poultry and humans worldwide. However, there has been limited research on these plasmids of S. Infantis isolated from eggs. Therefore, this study aimed to analyze the prevalence and characteristics of S. Infantis carrying the pESI-like plasmid from eggs in egg grading and packing plants. In this study, the pESI-like plasmid was only detected in 18 (78.3%) of 23 S. Infantis isolates, and it was absent in the other 9 Salmonella serovars. In particular, S. Infantis isolates carrying the pESI-like plasmid showed the significantly higher resistance to β-lactams, phenicols, cephams, aminoglycosides, quinolones, sulfonamides, and tetracyclines than Salmonella isolates without the pESI-like plasmid (p < 0.05). Moreover, all S. Infantis isolates carrying the pESI-like plasmid were identified as extended-spectrum β-lactamase (ESBL) producer, harboring the blaCTX-M-65 and blaTEM-1 genes, and carried non-β-lactamase resistance genes (ant(3\'\')-Ia, aph(4)-Ia, aac(3)-IVa, aph(3\')-Ic, sul1, tetA, dfrA14, and floR) against five antimicrobial classes. However, all isolates without the pESI-like plasmid only carried the blaTEM-1 gene among the β-lactamase genes, and either had no non-β-lactamase resistance genes or harbored non-β-lactamase resistance genes against one or two antimicrobial classes. Furthermore, all S. Infantis isolates carrying the pESI-like plasmid carried class 1 and 2 integrons and the aadA1 gene cassette, but none of the other isolates without the pESI-like plasmid harbored integrons. In particular, D87Y substitution in the gyrA gene and IncP replicon type were observed in all the S. Infantis isolates carrying the pESI-like plasmid but not in the S. Infantis isolates without the pESI-like plasmid. The distribution of pulsotypes between pESI-positive and pESI-negative S. Infantis isolates was clearly distinguished, but all S. Infantis isolates were classified as sequence type 32, regardless of whether they carried the pESI-like plasmid. This study is the first to report the characteristics of S. Infantis carrying the pESI-like plasmid isolated from eggs and can provide valuable information for formulating strategies to control the spread of Salmonella in the egg industry worldwide.
摘要：
在世界范围内的家禽和人类中一致报道了肠道沙门氏菌中新生婴儿链球菌(pESI)的质粒或pESI样质粒。然而,对从卵中分离出的这些婴儿链球菌质粒的研究有限。因此,本研究旨在分析在鸡蛋分级和包装植物中携带来自鸡蛋的pESI样质粒的婴儿链球菌的患病率和特征。在这项研究中,pESI样质粒仅在23株婴儿链球菌分离物中的18株(78.3%)中检测到，在其他9种沙门氏菌血清中没有。特别是,携带pESI样质粒的美国婴儿分离株对β-内酰胺的抗性明显更高，酚类化合物,Cephams,氨基糖苷类,喹诺酮类药物,磺胺类药物,和四环素比没有pESI样质粒的沙门氏菌分离株（p<0.05）。此外，所有携带pESI样质粒的婴儿分离株都被鉴定为超广谱β-内酰胺酶（ESBL）生产者，携带blaCTX-M-65和blaTEM-1基因，并携带非β-内酰胺酶抗性基因(ant(3\'\')-Ia，aph(4)-Ia,aac(3)-IVa,aph(3')-Ic，sul1,tetA,dfrA14和floR)针对五种抗菌类别。然而,所有没有pESI样质粒的分离株在β-内酰胺酶基因中仅携带blaTEM-1基因，并且没有非β-内酰胺酶抗性基因或具有针对一种或两种抗菌类别的非β-内酰胺酶抗性基因。此外，所有携带pESI样质粒的婴儿链球菌分离株携带1类和2类整合子和aadA1基因盒，但是没有pESI样质粒的其他分离株都没有整合子。特别是,在所有携带pESI样质粒的婴儿链球菌分离株中观察到gyrA基因和IncP复制子类型的D87Y取代，但在没有pESI样质粒的婴儿链球菌分离株中没有观察到。pESI阳性和pESI阴性S.Infantis分离株之间的脉型分布被清楚地区分。但所有婴儿链球菌分离株都被归类为32型序列,无论它们是否携带pESI样质粒.这项研究首次报道了从鸡蛋中分离出的携带pESI样质粒的婴儿链球菌的特征，可以为制定控制沙门氏菌在全球蛋业中传播的策略提供有价值的信息。
