IncX4 Plasmid Carrying the New mcr-1.9 Gene Variant in a CTX-M-8-Producing Escherichia coli Isolate Recovered From Swine
IncX4 Plasmid Carrying the New mcr-1.9 Gene Variant in a CTX-M-8-Producing Escherichia coli Isolate Recovered From Swine
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DOI：
10.3389/fmicb.2019.00367
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发表时间：
2019-03-14
影响因子：
5.2
通讯作者：
Canica, Manuela
中科院分区：
文献类型：
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作者：
Manageiro, Vera;Clemente, Lurdes;Canica, Manuela
我们研究了从葡萄牙屠宰场采集的猪盲肠样本中分离出的一株对大肠杆菌素具有耐药性的大肠杆菌。大肠埃希菌药敏表型分析coliLV 23529对粘菌素的最低抑菌浓度为4 mg/L时产生抗性。E. coli LV 23529中进行测序，并使用生物信息学工具分析组装的重叠群是否存在抗生素抗性和质粒复制子类型。我们报告了一种新的mcr-1基因变体（mcr-1.9），由IncX 4质粒携带，其中核苷酸T1238 C处的一点突变导致Val 413 Ala取代。mcr-1.9遗传背景的特征在于mcr-pap 2元件上游的IS 26元件和ISApl 1的缺失。生物信息学分析还揭示了赋予对β-内酰胺类、磺胺甲恶唑、甲氧苄啶、氯霉素和粘菌素抗性的基因，与所注意到的表型相对应。此外，我们强调了mcr-1.9 + bla（CTX-M-8）的存在，这是一种在欧洲动物源分离株中很少检出的bla（ESBL）基因;这两种基因分别位于33，303和89，458 bp的不同质粒上。携带MCR-1.9的质粒与世界范围内表征的其他携带X4型mcr-1的质粒具有高度同一性，这强烈表明在食用动物中存在PMCR编码基因（如MCR-1.9）对人类构成潜在威胁，因为它位于具有水平传播潜力的移动的遗传元件中。
We studied a commensal colistin-resistant Escherichia coli isolated from a swine cecum sample collected at a slaughter, in Portugal. Antimicrobial susceptibility phenotype of E. coli LV23529 showed resistance to colistin at a minimum inhibitory concentration of 4 mg/L. Whole genome of E. coli LV23529 was sequenced using a MiSeq system and the assembled contigs were analyzed for the presence of antibiotic resistance and plasmid replicon types using bioinformatics tools. We report a novel mcr-1 gene variant (mcr-1.9), carried by an IncX4 plasmid, where one-point mutation at nucleotide T1238C leads to Val413Ala substitution. The mcr-1.9 genetic context was characterized by an IS26 element upstream of the mcr-pap2 element and by the absence of ISApl1. Bioinformatic analysis also revealed genes conferring resistance to beta-lactams, sulphamethoxazole, trimethoprim, chloramphenicol and colistin, corresponding to the phenotype noticed. Moreover, we highlight the presence of mcr-1.9 plus bla(CTX-M-8), a bla(ESBL) gene rarely detected in Europe in isolates of animal origin; these two genes were located on different plasmids with 33,303 and 89,458 bp, respectively. MCR-1.9-harboring plasmid showed high identity to other X4-type mcr-1-harboring plasmids characterized worldwide, which strongly suggests that the presence of PMCR-encoding genes in food-producing animals, such as MCR-1.9, represent a potential threat to humans, as it is located in mobile genetic elements that have the potential to spread horizontally.