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Abstract：
BACKGROUND: Staphylococcus aureus, one of the most prevalent opportunistic pathogens, mainly colonizes the nasal cavity and is a risk factor for severe infections. Virulence factors and accessory gene regulator (agr) are key to the severity and diversity of staphylococcal infection. In this study, we aimed to characterise S. aureus agr-types and virulence genes and correlated them with genetic background and antibiotic-resistant phenotypes.
RESULTS: Agr types were identified in 704 isolates (98.5%), with only 11 isolates were negative for agr type. Most of our isolates were classified as agr type I, followed by types III, II and IV. The enterotoxin c gene (sec) was detected in 48.6% of isolates, showing the highest prevalence among the five enterotoxin genes detected. The positivity rates for the lukS/F-PV and tsst genes were 4% and 2.2%, respectively, while neither sed nor SasX were detected. ST45, ST59, ST338, ST188, ST6, ST7, ST22, ST25, ST398, and ST944 belonged to agr I group, while ST5 and ST15 belonged to agr II group. ST30 and ST1 were classified into agr III group, and ST121 was assigned into agr IV group. The tsst gene was found exclusively within agr I and III types belonging to ST7 and ST30 isolates, while the lukS/F-PV was predominantly carried by agr I type isolates primarily within CC59 and CC22 clones. Among the methicillin-resistant S. aureus (MRSA) isolates, 89.7% belonged to agr I group, and 97.8% of rifampicin-resistant or intermediate isolates were assigned to agr I group. MRSA isolates harboured more tested virulence genes compared to methicillin-susceptible S. aureus isolates.
CONCLUSIONS: We characterized the distributions of agr types and eight major virulence genes of 715 S. aureus isolates, and our findings revealed clear associations between agr types and STs, as well as virulence genes, and drug resistant phenotypes.
RESULTS: Agr types were identified in 704 isolates (98.5%), with only 11 isolates were negative for agr type. Most of our isolates were classified as agr type I, followed by types III, II and IV. The enterotoxin c gene (sec) was detected in 48.6% of isolates, showing the highest prevalence among the five enterotoxin genes detected. The positivity rates for the lukS/F-PV and tsst genes were 4% and 2.2%, respectively, while neither sed nor SasX were detected. ST45, ST59, ST338, ST188, ST6, ST7, ST22, ST25, ST398, and ST944 belonged to agr I group, while ST5 and ST15 belonged to agr II group. ST30 and ST1 were classified into agr III group, and ST121 was assigned into agr IV group. The tsst gene was found exclusively within agr I and III types belonging to ST7 and ST30 isolates, while the lukS/F-PV was predominantly carried by agr I type isolates primarily within CC59 and CC22 clones. Among the methicillin-resistant S. aureus (MRSA) isolates, 89.7% belonged to agr I group, and 97.8% of rifampicin-resistant or intermediate isolates were assigned to agr I group. MRSA isolates harboured more tested virulence genes compared to methicillin-susceptible S. aureus isolates.
CONCLUSIONS: We characterized the distributions of agr types and eight major virulence genes of 715 S. aureus isolates, and our findings revealed clear associations between agr types and STs, as well as virulence genes, and drug resistant phenotypes.
摘要：
背景：金黄色葡萄球菌，最普遍的机会病原体之一，主要定植于鼻腔，是严重感染的危险因素。毒力因子和辅助基因调节因子（agr）是葡萄球菌感染严重程度和多样性的关键。在这项研究中,我们旨在表征金黄色葡萄球菌agr型和毒力基因，并将它们与遗传背景和抗生素抗性表型相关联。
结果：在704个分离株（98.5%）中鉴定出Agr类型，只有11株agr型阴性。我们的大多数分离株被归类为agrI型，其次是类型III，II和IV。在48.6%的分离物中检测到肠毒素c基因(sec)，在检测到的五个肠毒素基因中，患病率最高。lukS/F-PV和tsst基因的阳性率分别为4%和2.2%,分别,而没有检测到sed和sasx。ST45、ST59、ST338、ST188、ST6、ST7、ST22、ST25、ST398和ST944属于agrI组，ST5和ST15属于agrⅡ组。ST30和ST1分为agrIII组，ST121被分配到agrIV组。tsst基因仅在属于ST7和ST30分离株的agrI和III型中发现，而lukS/F-PV主要由CC59和CC22克隆中的agrI型分离株携带。在耐甲氧西林金黄色葡萄球菌（MRSA）分离株中，89.7%属于agrI组，97.8%的利福平耐药或中间分离株被分配到agrI组。与甲氧西林敏感的金黄色葡萄球菌分离株相比，MRSA分离株具有更多的测试毒力基因。
结论：我们表征了715株金黄色葡萄球菌的agr类型和8个主要毒力基因的分布，我们的发现揭示了AGR类型和STs之间的明显关联，以及毒力基因，和耐药表型。
结果：在704个分离株（98.5%）中鉴定出Agr类型，只有11株agr型阴性。我们的大多数分离株被归类为agrI型，其次是类型III，II和IV。在48.6%的分离物中检测到肠毒素c基因(sec)，在检测到的五个肠毒素基因中，患病率最高。lukS/F-PV和tsst基因的阳性率分别为4%和2.2%,分别,而没有检测到sed和sasx。ST45、ST59、ST338、ST188、ST6、ST7、ST22、ST25、ST398和ST944属于agrI组，ST5和ST15属于agrⅡ组。ST30和ST1分为agrIII组，ST121被分配到agrIV组。tsst基因仅在属于ST7和ST30分离株的agrI和III型中发现，而lukS/F-PV主要由CC59和CC22克隆中的agrI型分离株携带。在耐甲氧西林金黄色葡萄球菌（MRSA）分离株中，89.7%属于agrI组，97.8%的利福平耐药或中间分离株被分配到agrI组。与甲氧西林敏感的金黄色葡萄球菌分离株相比，MRSA分离株具有更多的测试毒力基因。
结论：我们表征了715株金黄色葡萄球菌的agr类型和8个主要毒力基因的分布，我们的发现揭示了AGR类型和STs之间的明显关联，以及毒力基因，和耐药表型。
