There has been an increase in the number of reports on Salmonella enterica subsp. enterica serovar Infantis (S. Infantis) isolated from animals and humans. Recent studies using whole genome sequencing (WGS) have provided evidence on the likely contribution of a unique conjugative megaplasmid (pESI; ~280 kb) to the dissemination of this serovar worldwide. In the present study, twenty-two unrelated Salmonella strains [S. Infantis (n = 20) and Salmonella 6,7:r:- (n = 2)] and their plasmids were investigated using next generation sequencing technologies (MiSeq and MinION) to unravel the significant expansion of this bacteria in Turkey. Multi-locus sequence typing, plasmid replicons, resistance gene contents as well as phylogenetic relations between strains were determined. According to the WGS data, all S. Infantis possessed the relevant megaplasmid backbone genes and belonged to sequence type 32 (ST32) with the exception of a single novel ST7091. Tetracycline and trimethoprim/sulfamethoxazole resistance were found to be widespread in S. Infantis strains and the resistant strains exclusively carried the tetA, sul1, sul2 and dfrA14 genes. One S. Infantis isolate was also a carrier of the plasmid-mediated ampC via bla_CMY-2, gene. Moreover, full genomes of four S. Infantis isolates were reconstructed based on hybrid assembly. All four strains contained large plasmids (240–290 kb) similar to previously published megaplasmid (pESI) and accompanied by several small plasmids. The megaplasmid backbone contained a toxin-antitoxin system, two virulence cassettes and segments associated with heavy metals resistance, while variable regions possessed several antibiotic resistance genes flanked by mobile elements. This study indicated that pESI-like megaplasmid is widely disseminated within the tested S. Infantis strains of chicken meat, warranting further genomic studies on clinical strains from humans and animals to uncover the overall emergence and spread of this serovar.

关于肠沙门氏菌亚种的报道数量有所增加。从动物和人类中分离出的肠型血清型Infantis（S . Infantis）。最近使用全基因组测序（WGS）的研究提供了证据，证明独特的共轭大质粒（pESI;〜280 kb）可能在全世界传播这种血清型。在本研究中，22无关沙门氏菌菌株[小号。婴儿（n  = 20）和沙门氏菌6,7：r：-（n = 2）]，并使用下一代测序技术（MiSeq和MinION）研究了它们的质粒，以阐明该细菌在土耳其的显着扩增。确定了多基因座序列分型，质粒复制子，抗性基因含量以及菌株之间的系统发育关系。按照WGS数据，所有小号。除单个新颖的ST7091外，Infantis拥有相关的巨质粒骨架基因，属于序列类型32（ST32）。发现四环素和甲氧苄氨嘧啶/磺胺甲基异恶唑的耐药性在S中普遍存在。婴儿菌株和抗性菌株只携带的TET A，sul1，sul2和DFRA14基因。一个小号。婴儿分离株也是经由bla _CMY-2基因的质粒介导的ampC的载体。此外，四个S的完整基因组。婴儿分离株是基于混合装配而重建的。所有四个菌株均包含大型质粒（240–290 kb），类似于先前发表的大质粒（pESI），并伴有几个小型质粒。巨质粒骨架包含一个毒素-抗毒素系统，两个毒力盒和与重金属抗性有关的区段，而可变区拥有几个以移动元件为旁侧的抗生素抗性基因。这项研究表明，pESI样大质粒广泛分布在测试的S。鸡肉的Infantis菌株，需要对来自人和动物的临床菌株进行进一步的基因组研究，以揭示该血清型的整体出现和传播。