mcr-1 and mcr-2 variant genes identified in Moraxella species isolated from pigs in Great Britain from 2014 to 2015
mcr-1 and mcr-2 variant genes identified in Moraxella species isolated from pigs in Great Britain from 2014 to 2015
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DOI：
10.1093/jac/dkx286
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发表时间：
2017-10-01
影响因子：
5.2
通讯作者：
Anjum, Muna F.
中科院分区：
文献类型：
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作者：
AbuOun, Manal;Stubberfield, Emma J.;Anjum, Muna F.
目的：为了确定从英国健康猪中分离的革兰氏阴性菌中mcr-1和mcr-2基因的存在情况。方法：采用WGS对2014年至2015年期间从猪中分离的革兰氏阴性菌（n=657）进行检查。从英国六个农场收集的健康猪屠宰时的混合盲肠内容物中分离。其他细菌，包括来自相同农场的大肠埃希菌，未检出携带mcr-1或mcr-2。猪莫拉菌样分离株MSG 13-C 03携带MCR-1.10，与MCR-1的同源性为98.7%;多菌莫拉菌样分离株MSG 47-C17携带MCR-2.2变异株，与MCR-2的同源性为87.9%。大肠杆菌的最低抑菌浓度为1-2 mg/L。在MSG 13-C 03和MSG 47-C17中均未鉴定出完整的插入元件，尽管MSG 13-C 03含有与在E. coli质粒与插入的2.6kb片段同源性达97%。6株Osloensis莫拉菌EptA阳性。它们与MCR-1和MCR-2的同源性为62%-64.5%，粘杆菌素的MIC为2 - 4 mg/L。系统发育分析表明，MCR和EptA是从一个共同的祖先进化而来的。除mcr基因外，两株菌株均携带有β-内酰胺酶基因blaBRO-1，而MSG 47-C17菌株均携带有四环素耐药基因tetL。结论：本研究进一步证实了莫拉菌mcr-pap 2基因通过复合转座子的动员作用而导致其全球性传播。最近莫拉菌分离株中mcr-pap 2的存在表明它们可能包含mcr的储存库。
Objectives: To determine the occurrence of mcr-1 and mcr-2 genes in Gram-negative bacteria isolated from healthy pigs in Great Britain.Methods: Gram-negative bacteria (n=657) isolated from pigs between 2014 and 2015 were examined by WGS.Results: Variants of mcr-1 and mcr-2 were identified in Moraxella spp. isolated from pooled caecal contents of healthy pigs at slaughter collected fromsix farms in Great Britain. Other bacteria, including Escherichia coli from the same farms, were not detected harbouring mcr-1 or mcr-2. A Moraxella porci-like isolate, MSG13-C03, harboured MCR-1.10 with 98.7% identity to MCR-1, and a Moraxella pluranimalium-like isolate, MSG47-C17, harboured an MCR-2.2 variant with 87.9% identity to MCR-2, from E. coli; the isolates had colistin MICs of 1-2 mg/L. No intact insertion elements were identified in either MSG13-C03 or MSG47-C17, although MSG13-C03 harboured the conserved nucleotides abutting the ISApl1 composite transposon found in E. coli plasmids and the intervening similar to 2.6 kb fragment showed 97% identity. SixMoraxella osloensis isolateswere positive for phosphoethanolamine transferase (EptA). They shared 62%-64.5% identity to MCR-1 and MCR-2, with colistin MICs from 2 to 4mg/L. Phylogenetic analysis indicated that MCR and EptA have evolved froma common ancestor. In addition to mcr, the b-lactamase gene, blaBRO-1, was found in both isolates, whilst the tetracycline resistance gene, tetL, was found inMSG47-C17.Conclusions: Our results add further evidence for the mobilization of the mcr-pap2 unit from Moraxella via composite transposons leading to its global dissemination. The presence of mcr-pap2 from recent Moraxella isolates indicates they may comprise a reservoir for mcr.