Community-associated Methicillin-Resistant Staphylococcus aureus (CA-MRSA) is notorious as a leading cause of soft tissue infections. Despite several studies on the Agr regulator, the mechanisms of action of Agr on the virulence factors in different strains are still unknown. To reveal the role of Agr in different CA-MRSA, we investigated the LACΔagr mutant and the MW2Δagr mutant by comparing LAC (USA300), MW2 (USA400), and Δagr mutants. The changes of Δagr mutants in sensitivity to oxacillin and several virulence factors, such as biofilm formation, pigmentation, motility, and membrane properties, were monitored. LACΔagr and MW2Δagr mutants showed different oxacillin sensitivity and biofilm formation compared to the LAC and MW2 strains. Regardless of the strain, the motility was reduced in Δagr mutants. And there was an increase in the long chain fatty acid in phospholipid fatty acid composition of Δagr mutants. Other properties, such as biofilm formation, pigmentation, motility, and membrane properties, were different in both Δagr mutants. The Agr regulator may have a common role like the control of motility and strain-dependent roles such as antibiotic resistance, biofilm formation, change of membrane, and pigment production. It does not seem easy to control all MRSA by targeting the Agr regulator only as it showed strain-dependent behaviors.

中文翻译：

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USA300 和 USA400 社区相关耐甲氧西林金黄色葡萄球菌 (CA-MRSA) 中辅助基因调节因子 (Agr) 行为差异的比较研究。

社区相关的耐甲氧西林金黄色葡萄球菌(CA-MRSA) 是臭名昭著的软组织感染的主要原因。尽管对 Agr 调节器进行了多项研究，但 Agr 对不同菌株毒力因子的作用机制仍然未知。为了揭示 Agr 在不同 CA-MRSA 中的作用，我们通过比较 LAC (USA300)、MW2 (USA400) 和 Δ agr突变体研究了 LACΔ agr突变体和 MW2Δ agr突变体。监测了 Δ agr突变体对苯唑西林和几种毒力因子（如生物膜形成、色素沉着、运动性和膜特性）敏感性的变化。LACΔagr和MW2Δagr _与 LAC 和 MW2 菌株相比，突变体显示出不同的苯唑西林敏感性和生物膜形成。无论菌株如何，Δagr突变体的运动性都降低了。并且Δagr突变体的磷脂脂肪酸组成中的长链脂肪酸增加。其他特性，如生物膜形成、色素沉着、运动性和膜特性，在两种Δagr突变体中都不同。Agr 调节器可能具有共同的作用，如运动控制和菌株依赖性作用，如抗生素抗性、生物膜形成、膜变化和色素产生。仅通过针对 Agr 调节器来控制所有 MRSA 似乎并不容易，因为它显示出应变依赖性行为。