Whole genome sequencing for analyzing mutation sites in linezolid-resistant methicillin-resistant Staphylococcus aureus / 中国感染控制杂志

ABSTRACT

Objective To understand genetic mutation sites in linezolid (LZD)-sensitive and inducible resistant strains of methicillin-resistant Staphylococcus aureus (MRSA) using whole-genome sequencing,and realize mutation sites of LZD-resistant gene.Methods MRSA-MS4 with explicit genotype and whole-genome sequences was induced by LZD of different concentration gradients,LZD-resistant strain MRSA-MS4-LZD100 was obtained,minimum inhibitory concentration(MIC) was detected,domain V of 23S rRNA and ribosomal proteins L3/L4 gene in MRSAMS4-LZD100 were amplified by polymerase chain reaction (PCR),the sequenced products obtained the corresponding mutation site in contrast with the wild-type strain;Illumina PE library was constructed through paired-end sequencing by Illumina HiSeq 2000 technique,and whole genome sequencing was completed based on bioinformatics.Results MRAS-MS4-LZD100 strain was induced after 32 passages,MIC of LZD was 96 μg/mL.Sequencing of PCR products indicated the genetic variations were G2447T mutation in multiple copies of domain V of 23S rRNA gene,and Gly113Val mutation in L3 protein respectively;the whole genome of MRSA-MS4-LZD100 contained 2 744 315 bp,annotation of the whole genome found a total of 2 509 genes,11 tRNA-encoding genes and 2 entire rRNA-encoding operons.The data were submitted to the PubMed,and the GeneBank accession number JXMJ00000000 was assigned;a total of 101 SNPs and 6 Small indels were found,16 of 101SNP mutations occurred in exon,of which the variant proteins with anmino acid sequence alterations included IstB ATP binding domain-containing protein,clumping factor A,IS1272 transposase and so on;3 of 6 Small indel mutations occurred in exon,of which the variant proteins with anmino acid sequence alterations included hypothetical protein,30S ribosomal protein S1,and clumping factor A.Conclusion LZD-resistant strain MRSA-MS4-LZD100 was successfully induced by LZD;beside 23S rRNA V domain and ribosomal L3 protein,the other mutant site exist in this resistant strain,which provide some direction for subsequent study of recessive LZD resistance mechanism.