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首页> 外文期刊>Injury >The small colony variant (SCV) concept -- the role of staphylococcal SCVs in persistent infections.
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The small colony variant (SCV) concept -- the role of staphylococcal SCVs in persistent infections.

机译：小菌落变体（SCV）概念-葡萄球菌SCV在持续感染中的作用。

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The recovery of small colony variants (SCVs) from clinical specimens was first described at the beginning of the last century. However, not until the past decade was an association of these variants with chronic, recurrent, and persistent infections such as chronic osteomyelitis and persistent skin and softtissue infection described. Since then, a number of reports and prospective studies have supported a pathogenic role for SCVs in disease. Biochemical and other characteristics of SCVs have suggested a link between electron-transport defective SCV strains and persistent infections, however, the strains examined were genetically undefined SCVs. Therefore, a stable mutant in electron transport was generated by interrupting one of the hemin biosynthetic genes, hemB, in Staphylococcus aureus. This mutant showed characteristics typical of clinical SCVs such as slow growth, decreased pigment formation, low coagulase activity, reduced hemolytic activity, and resistance to aminoglycosides. Furthermore, the mutant was able to persist within cultured endothelial cells due to decreased a-toxin production. It was suggested that the intracellular location of this subpopulation might shield the variants from host defenses and antibiotics, thus providing one explanation for the difficulty in removing SCVs from host tissues. Therefore, a defect in the electron-transport system allows S. aureus SCVs to resist aminoglycosides and persist intracellularly. Because of their fastidious growth characteristics, they are easily missed or misidentified in the clinical laboratory. Therefore, when an infection persists for weeks or months or fails to respond to antimicrobial therapy, clinicians as well as laboratory personnel should consider further efforts to search for this staphylococcal subpopulation.
机译：上世纪初首次描述了从临床标本中回收小菌落变体（SCV）。但是，直到最近十年，这些变种才与慢性，复发性和持续性感染（例如慢性骨髓炎以及持续性皮肤和软组织感染）相关联。从那以后，许多报道和前瞻性研究支持了SCV在疾病中的致病作用。 SCV的生化和其他特征表明，电子运输缺陷SCV菌株与持续感染之间存在联系，但是，所检测的菌株是遗传上不确定的SCV。因此，通过中断金黄色葡萄球菌中的一种血红素生物合成基因hemB，可以产生一个稳定的电子传输突变体。此突变体表现出临床SCV的典型特征，例如生长缓慢，色素形成减少，凝固酶活性低，溶血活性降低以及对氨基糖苷类的耐药性。此外，由于α-毒素产生减少，该突变体能够在培养的内皮细胞内持续存在。有人提出，该亚群的细胞内位置可能使变异体免受宿主防御和抗生素的影响，从而为从宿主组织中去除SCV的困难提供了一种解释。因此，电子传输系统中的缺陷使金黄色葡萄球菌SCV能够抵抗氨基糖苷并在细胞内持续存在。由于它们具有良好的生长特性，因此在临床实验室中很容易遗漏或误认。因此，当感染持续数周或数月或对抗菌治疗无效时，临床医生和实验室人员应考虑进一步努力以寻找这种葡萄球菌亚群。

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