Department of Veterinary Medicine & Institute of Preventive Veterinary Sciences, Zhejiang University College of Animal Sciences, Hangzhou, China.
Department of Veterinary Medicine & Institute of Preventive Veterinary Sciences, Zhejiang University College of Animal Sciences, Hangzhou, China.
Vet Microbiol. 2023 Mar;278:109634. doi: 10.1016/j.vetmic.2022.109634. Epub 2022 Dec 17.
The emergence and dissemination of the extended spectrum β-lactamase (ESBL)-producing Enterobacteriaceae harbouring antimicrobial resistance (AMR) genes has diminished the potential options for treating multidrug-resistant (MDR) bacterial infections. Until now, numerous studies reported the spreading of critical plasmid-borne AMR genes from different sources worldwide. While the knowledge on the occurrence of the plasmid-borne AMR genes, especially mcr genes in the dead chick embryos, remains obscure. A retrospective study was conducted to detect the presence of the mcr genes in forty-five Salmonella enterica isolates recovered from 2139 dead chick embryo samples, from breeding chicken hatcheries in Henan, China. Using multiplex PCR, we found only four isolates out of the forty-five were mcr-9-positive. These four isolates were found to be MDR, ESBL- producing and showed resistance to 10 antimicrobial drugs. Additionally, mcr-9 harbouring plasmids were successfully transferred into Escherichia coli (E. coli) J53 by conjugation and the mcr-9 gene was confirmed by PCR. We also found that the transconjugants exhibited higher MICs for ampicillin, gentamycin and colistin than the recipient. Whole-genome sequence analysis showed that the four isolates belonged to Salmonella Thompson ST26 and harboured IncHI2 plasmid replicon. Furthermore, the mcr-9 harbouring plasmids were reconstructed using in silico tools and found to be carried other AMR genes (bla and qnrB4). The studied isolates carried the typical virulence factors from Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2), in addition to pef and csg operons which are important in host adhesion and biofilm formation. The mgtC gene, which is involved in phagocytosis, has also been identified. Together, the increase in the phenotypic resistance of the transconjugants and the plasmid in silico reconstruction analysis confirmed that the corresponding resistance genes might be located together on the same plasmid. To track the potential phylogenomic relations of our detected ESBL S. Thompson isolates, we constructed a phylogenomic tree with available ESBL S. Thompson genomes (n = 26) that were reported worldwide. The studied isolates were independently clustered together with four other Chinese isolates of food origin in one clade, providing strong evidence of a potential recent and wide dissemination of ESBL S. Thompson across the food chain in China. In conclusion, we report the detection of four highly virulent ESBL-producing S. Thompson ST26 isolates harbouring mcr-9 gene obtained from dead chick embryos in Henan, China.
产extended spectrum β-lactamase (ESBL)的肠杆菌科细菌的出现和传播，使治疗多重耐药 (MDR) 细菌感染的潜在选择减少。到目前为止，许多研究报告了来自世界各地不同来源的关键质粒携带的 AMR 基因的传播。然而，关于质粒携带的 AMR 基因，特别是 mcr 基因在死鸡胚中的存在情况仍然不清楚。一项回顾性研究检测了来自中国河南种鸡孵化场的 2139 只死鸡胚样本中分离的 45 株沙门氏菌中 mcr 基因的存在情况。使用多重 PCR，我们发现 45 株分离株中只有 4 株 mcr-9 阳性。这 4 株分离株为 MDR、产 ESBL 且对 10 种抗菌药物耐药。此外，mcr-9 携带的质粒通过接合成功转移到大肠杆菌 (E. coli) J53 中，通过 PCR 证实了 mcr-9 基因的存在。我们还发现，与受体相比，转导子对氨苄西林、庆大霉素和粘菌素的 MICs 更高。全基因组序列分析表明，这 4 株分离株属于沙门氏菌 Thompson ST26，携带 IncHI2 质粒复制子。此外，使用计算机模拟工具重建了携带 mcr-9 的质粒，并发现其携带其他 AMR 基因（bla 和 qnrB4）。研究分离株携带沙门氏菌致病性岛 1 和 2（SPI-1 和 SPI-2）的典型毒力因子，以及在宿主黏附和生物膜形成中起重要作用的 pef 和 csg 操纵子。还鉴定了参与吞噬作用的 mgtC 基因。转导子表型耐药性的增加和质粒计算机模拟重建分析共同证实，相应的耐药基因可能位于同一质粒上。为了追踪我们检测到的产 ESBL 沙门氏菌 Thompson 分离株的潜在系统基因组关系，我们构建了一个包含全球报道的 26 株产 ESBL 沙门氏菌 Thompson 基因组的系统基因组树。研究分离株与来自中国的另外 4 株食品源分离株一起独立聚类在一个分支中，这为 ESBL 沙门氏菌 Thompson 在中国食物链中的潜在近期广泛传播提供了有力证据。总之，我们报告了在中国河南从死鸡胚中分离到的 4 株产 extended spectrum β-lactamase (ESBL) 的高毒力沙门氏菌 Thompson ST26 携带 mcr-9 基因。
