Cepheid, 904 Caribbean Drive, Sunnyvale, CA, United States.
Creighton University School of Medicine, Omaha, NE, United States.
Diagn Microbiol Infect Dis. 2020 Dec;98(4):115175. doi: 10.1016/j.diagmicrobio.2020.115175. Epub 2020 Aug 15.
Approximately 15-20% of the S. aureus genome contains mobile genetic elements that can cause discrepancies between phenotypic and genotypic identification methods. Three blood culture bottles (each from a different patient) that showed discordant results, were shown to contain 2 S. aureus isolates after additional subcultures. One bottle had MRSA and MSSA that by DNA sequence analysis differed only by 31 kb; however, the deletions encompassed parts of SCCmec including mecA and SCC. The second bottle contained MRSA and MSSA that differed by 124 kb; the MSSA was missing the entire SCCmec and spa regions. The last bottle contained 2 MRSA, one with ACME II disrupting SCCmec and a 24 bp spa deletion. The deletions in SCCmec and the other elements gave rise to the discrepancies between molecular and the original culture results. Such discrepancies should prompt a search for additional strains in the blood culture bottle.
金黄色葡萄球菌基因组的大约 15-20%包含可导致表型和基因型鉴定方法之间出现差异的移动遗传元件。经过进一步的传代培养，3 个血培养瓶（每个来自不同的患者）显示出不一致的结果，其中含有 2 株金黄色葡萄球菌分离株。一瓶含有 MRSA 和 MSSA，通过 DNA 序列分析，两者仅相差 31kb；然而，缺失部分包括 SCCmec，包括 mecA 和 SCC。第二瓶含有 MRSA 和 MSSA，相差 124kb；MSSA 缺失整个 SCCmec 和 spa 区域。最后一瓶含有 2 株 MRSA，一株携带 ACME II 破坏 SCCmec 和 24bp spa 缺失。SCCmec 和其他元件的缺失导致了分子和原始培养结果之间的差异。这种差异应促使在血培养瓶中寻找其他菌株。
