Staphylococcus epidermidis is a leading cause of nosocomial infections in patients with a compromised immune system and/or an implanted medical device. Seventy to 90% of S. epidermidis clinical isolates are methicillin resistant and carry the mecA gene, present in a mobile genetic element (MGE) called the staphylococcal cassette chromosome mec (SCCmec) element. Along with the presence of antibiotic and heavy metal resistance genes, MGEs can also contain genes encoding secreted or cell wall-anchored virulence factors. In our earlier studies of S. epidermidis clinical isolates, we discovered S. epidermidis surface protein J (SesJ), a prototype of a recently discovered subfamily of the microbial surface component recognizing adhesive matrix molecule (MSCRAMM) group. MSCRAMMs are major virulence factors of pathogenic Gram-positive bacteria. Here, we report that the sesJ gene is always accompanied by two glycosyltransferase genes, gtfA and gtfB, and is present in two MGEs, called the arginine catabolic mobile element (ACME) and the staphylococcal cassette chromosome (SCC) element. The presence of the sesJ gene was associated with the left-hand direct repeat DR_B or DR_E. When inserted via DR_E, the sesJ gene was encoded in the SCC element. When inserted via DR_B, the sesJ gene was accompanied by the genes for the type 1 restriction modification system and was encoded in the ACME. Additionally, the SCC element and ACME carry different isoforms of the SesJ protein. To date, the genes encoding MSCRAMMs have been seen to be located in the bacterial core genome. Here, we report the presence of an MSCRAMM in an MGE in S. epidermidis clinical isolates.IMPORTANCE S. epidermidis is an opportunistic bacterium that has established itself as a successful nosocomial pathogen. The modern era of novel therapeutics and medical devices has extended the longevity of human life, but at the same time, we also witness the evolution of pathogens to adapt to newly available niches in the host. Increasing antibiotic resistance among pathogens provides an example of such pathogen adaptation. With limited opportunities to modify the core genome, most of the adaptation occurs by acquiring new genes, such as virulence factors and antibiotic resistance determinants present in MGEs. In this study, we describe that the sesJ gene, encoding a recently discovered cell wall-anchored protein in S. epidermidis, is present in both ACME and the SCC element. The presence of virulence factors in MGEs can influence the virulence potential of a specific strain. Therefore, it is critical to study the virulence factors found in MGEs in emerging pathogenic bacteria or strains to understand the mechanisms used by these bacteria to cause infections.

中文翻译：

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表皮葡萄球菌 MSCRAMM SesJ 在复合岛中编码。


表皮葡萄球菌是免疫系统受损和/或植入医疗设备的患者发生院内感染的主要原因。 70% 至 90% 的表皮葡萄球菌临床分离株对甲氧西林具有抗药性，并携带 mecA 基因，该基因存在于称为葡萄球菌盒式染色体 mec (SCCmec) 元件的移动遗传元件 (MGE) 中。除了抗生素和重金属抗性基因的存在外，MGE 还可能含有编码分泌型或细胞壁锚定毒力因子的基因。在我们早期对表皮葡萄球菌临床分离株的研究中，我们发现了表皮葡萄球菌表面蛋白 J (SesJ)，它是最近发现的微生物表面成分识别粘附基质分子 (MSCRAMM) 组亚科的原型。 MSCRAMM 是致病性革兰氏阳性菌的主要毒力因子。在这里，我们报道sesJ基因总是伴随着两个糖基转移酶基因gtfA和gtfB，并且存在于两个MGE中，称为精氨酸分解代谢移动元件（ACME）和葡萄球菌盒式染色体（SCC）元件。 sesJ 基因的存在与左侧同向重复序列 DR_B 或 DR_E 相关。当通过 DR_E 插入时，sesJ 基因被编码在 SCC 元件中。当通过 DR_B 插入时，sesJ 基因伴随着 1 型限制性修饰系统的基因，并在 ACME 中编码。此外，SCC 元件和 ACME 携带不同的 SesJ 蛋白亚型。迄今为止，编码 MSCRAMM 的基因已被发现位于细菌核心基因组中。在这里，我们报告了表皮葡萄球菌临床分离株的 MGE 中存在 MSCRAMM。 重要性 表皮葡萄球菌是一种机会性细菌，已成为一种成功的医院病原体。 现代新型疗法和医疗设备延长了人类的寿命，但与此同时，我们也见证了病原体的进化，以适应宿主体内新的生态位。病原体中抗生素耐药性的增加提供了这种病原体适应的一个例子。由于修改核心基因组的机会有限，大多数适应都是通过获取新基因来实现的，例如 MGE 中存在的毒力因子和抗生素耐药性决定因素。在这项研究中，我们描述了 sesJ 基因，编码最近在表皮葡萄球菌中发现的细胞壁锚定蛋白，存在于 ACME 和 SCC 元件中。 MGE 中毒力因子的存在可以影响特定菌株的毒力潜力。因此，研究新兴致病菌或菌株中 MGE 的毒力因子对于了解这些细菌引起感染的机制至关重要。