螺旋霉素对金黄色葡萄球菌耐药突变体的转录组特征分析

Transcriptomic analysis of a spiramycin Ⅰ-resistant Staphylococcus aureus mutant

螺旋霉素Ⅰ是一类重要的大环内酯类抗生素,但由于耐药菌的产生限制了临床使用。为了在转录水平上全局性的了解细菌耐药前后对抗生素响应上的变化和机制,通过基于RNA-seq方法对螺旋霉素敏感菌株Staphylococcus aureus ATCC29213和其诱导耐药突变菌株S.aureus ATCC29213-R在抗生素压力诱导前后菌体的转录组表达变化进行了分析。研究结果证明了螺旋霉素Ⅰ可诱导S.aureus ATCC29213产生耐药菌株,并通过测序发现该菌的23S rRNA 2089位A→C颠换,该突变位点在S.aureus中是首次报道。此外,还发现螺旋霉素Ⅰ能使S.aureus ATCC29213-R菌株的322个基因上调,82个基因下调,其中涉及精氨酸降解的基因arc A,arc C和arg F表达水平分别上调35,18.05和30.84倍,涉及精氨酸合成的基因arg H和arg G分别下调13.51和21.45倍,其综合作用减少精氨酸的内源性合成;因此,精氨酸代谢途径可能成为治疗23S RNA突变耐药金黄色葡萄球菌感染新的潜在靶点。

The clinical utility of macrolide antibiotics has declined due to the appearance of resistant isolates.A spiramycin I-resistant Staphylococcus aureus ATCC29213-R was induced and isolated with increasing the concentration of spiramycin I,which exhibits an A→C transversion at position 2089 in the 23 S rRNA gene,which is first reported in the S.aureus.A RNA-seq based transcriptomic analysis was performed to understand the overall response of resistant bacteria to spiramycin I treatment with subinhibitory dosage.In this study,There are a total of 322 up-regulated and 82 down-regulated genes in spiramycin I-treated S.aureus ATCC29213-R and 426 upregulated,838 down-regulated in spiramycin I-treated S.aureus ATCC29213,which were identified differentially expressed compared to their control with a minimum 2-fold change（Q 0.05）.Interestingly,The data showed that arg H and arg G transcripts,in the arginine biosynthetic pathway,were decreased by 13.51-fold and 21.45-fold,respectively,compared to the control,while the expression level of three genes involved in arginine catabolism,arc A,arc C,and arg F,increased by 35-fold,18.05-fold and 30.84-fold,respectively.The results revealed that spiramycin I could trigger the up-regulation of the genes of ACME-Arc system which allows S.aureus to survive in acidic environments of human skin.This suggesed the arginine-deiminase pathway may be a potential target for treatment of the resistant S.aureus.