Li Jun, Liu Shuyan, Fu Jiafang, Yin Jianhua, Zhao Jia, Zhong Chuanqing, Cao Guangxiang
1 School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, China.
2 College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China.
Microb Drug Resist. 2019 Apr;25(3):317-325. doi: 10.1089/mdr.2018.0418. Epub 2019 Mar 13.
Development of antibiotic resistance can be achieved either by mutation or by acquiring a resistance gene from foreign sources, with some resistance genes likely originating in microbial populations to counteract antibiotics present in natural ecosystems. In this study, we describe the first report of a strain of nonclinical multidrug-resistant Stenotrophomonas sp. strain G4 with high-level resistance to colistin and meropenem, phylogenetically distinct from well-studied multiple drug-resistant species of Stenotrophomonas maltophilia. As the high-level colistin resistance of this strain was of great concern, the genome of this strain was completely sequenced. Only one chromosome was identified, and no plasmids were found. Chromosomal gene variants and other potential genetic determinants conferring resistance to colistin and meropenem were comparatively analyzed, and results showed that strain G4 harbored two putative colistin resistance determinants (named mcr-5.3 and mcr-8.2) and four extended-spectrum β-lactamase genes. In addition, 12 genes potentially encoding seven different types of efflux pumps were identified, which may have a major role in acquisition/transfer of colistin resistance. Our discovery of multiple antibiotic resistance determinants in this environmental strain extensively expands our understanding of the extent of dissemination of colistin and meropenem resistance.
抗生素耐药性的产生可以通过突变或从外源获得耐药基因来实现，一些耐药基因可能起源于微生物种群，以对抗自然生态系统中存在的抗生素。在本研究中，我们报道了首例非临床多药耐药嗜麦芽窄食单胞菌菌株G4，该菌株对黏菌素和美罗培南具有高水平耐药性，在系统发育上与已深入研究的嗜麦芽窄食单胞菌多重耐药菌株不同。由于该菌株对黏菌素的高水平耐药性备受关注，我们对其基因组进行了全测序。结果仅鉴定出一条染色体，未发现质粒。我们对赋予黏菌素和美罗培南耐药性的染色体基因变体和其他潜在遗传决定因素进行了比较分析，结果显示菌株G4含有两个假定的黏菌素耐药决定因素（命名为mcr - 5.3和mcr - 8.2）以及四个超广谱β-内酰胺酶基因。此外，还鉴定出12个可能编码七种不同类型外排泵的基因，这些基因可能在黏菌素耐药性的获得/转移中起主要作用。我们在这一环境菌株中发现多种抗生素耐药决定因素，极大地扩展了我们对黏菌素和美罗培南耐药性传播范围的认识。
