Choi Myeongjin, Ko Kwan Soo
Department of Microbiology, Sungkyunkwan University School of Medicine, Suwon 16419, Korea.
Antibiotics (Basel). 2020 Jul 2;9(7):374. doi: 10.3390/antibiotics9070374.
The present study was undertaken to find novel genes associated with colistin resistance in . Five colistin-resistant mutants were derived from four colistin-susceptible parental strains belonging to different clones. Whole-genome sequencing was performed for the nine strains to screen altered candidate genes. Expression levels of genes with amino acid alterations in derivative strains were determined using quantitative real-time Polymerase chain reaction (PCR). Colistin susceptibility was examined in a parental strain complemented with altered candidate genes. Overall, 13 genetic alterations were identified in five pairs of isogenic strains. Genetic alterations related to , including the insertion of an IS-like element in an intergenic or coding region and amino acid substitutions, were identified in three separate derivative strains. Amino acid substitutions and deletion of PhoQ were determined in one derivative strain. With inactivation of CrrA and substituted CrrB, amino acid substitutions and deletion were identified in a repressor of operon () and hypothetical protein (), respectively. Decreased colistin susceptibility was observed in a parental strain complemented with KP1-0061, but not a KP1-3620 gene. This study demonstrated diverse genetic paths to colistin resistance in . Our results suggest that a repressor of operon may play an important role in colistin resistance in .
本研究旨在寻找与大肠埃希菌中黏菌素耐药性相关的新基因。从属于不同克隆的4株黏菌素敏感亲代菌株中获得了5株黏菌素耐药突变体。对这9株菌株进行全基因组测序以筛选出发生改变的候选基因。使用定量实时聚合酶链反应（PCR）测定衍生菌株中发生氨基酸改变的基因的表达水平。在互补了发生改变的候选基因的亲代菌株中检测黏菌素敏感性。总体而言，在5对同基因菌株中鉴定出13处基因改变。在3个不同的衍生菌株中鉴定出与大肠埃希菌相关的基因改变，包括在基因间区域或编码区域插入一个类插入序列元件以及氨基酸替换。在一个衍生菌株中确定了PhoQ的氨基酸替换和缺失。随着CrrA的失活和CrrB的替代，分别在操纵子（）的阻遏物和假定蛋白（）中鉴定出氨基酸替换和缺失。在互补了KP1 - 0061但未互补KP1 - 3620基因的亲代菌株中观察到黏菌素敏感性降低。本研究证明了大肠埃希菌中黏菌素耐药性的多种遗传途径。我们的结果表明，操纵子的阻遏物可能在大肠埃希菌的黏菌素耐药性中起重要作用。
