The United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu, Japan.
Department of Microbiology, Osaka Institute of Public Health, Osaka, Japan.
J Glob Antimicrob Resist. 2022 Sep;30:152-154. doi: 10.1016/j.jgar.2022.06.007. Epub 2022 Jun 12.
The extensive spread of colistin resistance represents an enormous concern to infectious disease treatment, because colistin is one of the few effective antibiotics against multidrug-resistant bacterial infections, including carbapenem-resistant bacteria. This dissemination can be caused by plasmid transfer containing the colistin resistance gene mcr. Therefore, the plasmid host range affects horizontal gene transfer. This study reports a fusion plasmid of different incompatibility types, which could easily expand the plasmid host range, allowing widespread mcr prevalence in the microbial community.
Genome sequences of colistin-resistant Escherichia coli isolates from stool specimens of healthy human residents in Ecuador were determined using the DNBSEQ and MinION platforms. Hybrid genome assembly was performed using Unicycler, and the genomes were annotated using DFAST. Genome analysis was performed using the Geneious Prime software.
Two colistin-resistant E. coli strains isolated separately from different residents presented mcr-carrying plasmids with fused different incompatibility types, IncFIA, IncHIIA, and IncHIIB. The phylogenies of these host bacteria were different. The sizes of the mcr-carrying fusion plasmids pLR-06 and pLR-50 with the full Tn6330 mcr-transposon were 260 Kbp and 198 Kbp, respectively. Both fusion plasmids possessed other resistance genes, including tet(B), tet(M), bla, sul3, cmlA1, aadA1, aadA2, fosA3, and dfrA12.
This is the first report of a fusion plasmid comprising different incompatibility types with mcr from colistin-resistant E. coli strains isolated from community residents. The mcr fusion plasmid may play a crucial role in achieving horizontal mcr transmission and the evolution of the multidrug resistance plasmid among hosts.
多粘菌素耐药性的广泛传播对传染病治疗构成了巨大威胁，因为多粘菌素是少数几种对抗包括碳青霉烯类耐药菌在内的多重耐药菌感染的有效抗生素之一。这种传播可能是由含有多粘菌素耐药基因 mcr 的质粒转移引起的。因此，质粒的宿主范围会影响水平基因转移。本研究报告了一种不同不相容性类型的融合质粒，它可以很容易地扩大质粒的宿主范围，使微生物群落中广泛存在 mcr。
使用 DNBSEQ 和 MinION 平台测定来自厄瓜多尔健康居民粪便标本中分离的多粘菌素耐药大肠杆菌分离株的基因组序列。使用 Unicycler 进行混合基因组组装，使用 DFAST 进行基因组注释。使用 Geneious Prime 软件进行基因组分析。
从不同居民中分别分离的两株多粘菌素耐药大肠杆菌菌株携带带有不同不相容性类型融合的 mcr 质粒，IncFIA、IncHIIA 和 IncHIIB。这些宿主细菌的系统发育不同。携带完整 Tn6330 mcr 转座子的 mcr 携带融合质粒 pLR-06 和 pLR-50 的大小分别为 260 Kbp 和 198 Kbp。两个融合质粒都携带其他耐药基因，包括 tet(B)、tet(M)、bla、sul3、cmlA1、aadA1、aadA2、fosA3 和 dfrA12。
这是首次从社区居民分离的多粘菌素耐药大肠杆菌菌株中报告了一种包含不同不相容性类型 mcr 的融合质粒。mcr 融合质粒可能在实现水平 mcr 传播和宿主间多药耐药质粒的进化中发挥关键作用。
