BACKGROUND Staphylococcus aureus bloodstream infections (BSI) cause significant morbidity and mortality due to the frequent antibiotic resistance, toxin and adhesin production of the bacterium. These characteristics differ significantly in methicillin resistant (MRSA) and methicillin sensitive S. aureus (MSSA) and also among isolates of different MRSA clones, contributing to the outcome of S. aureus bacteraemia. METHODS In this study, all MRSA BSI isolates from Semmelweis University, Budapest, Hungary, isolated between 2011-2016 and the same number of matched MSSA (overall 306 isolates) were characterised in terms of antibiotic susceptibility, virulence genes, clonality and their association with all-cause 30-day mortality. Effect of patient related variables, such as age, gender and comorbidities were also investigated. RESULTS ST22-MRSA-IV and ST5-MRSA-II were the most prevalent clones in our study. SCCmec I isolates showed the highest resistance rates and SCCmec II carried most virulence genes. Infections caused by SCCmec IV isolates were associated with the highest mortality rate (42.2%), despite the similar comorbidity rates of the different patient groups. All-cause 30-day mortality was 39.9% in the MRSA and 30.7% in the MSSA group. Increased teicoplanin MIC was associated with high mortality rate. Resistance to ciprofloxacin, erythromycin and clindamycin was common in MRSA, whereas MSSA isolates were more sensitive to all antibiotics with the exception of doxycycline. All MRSA isolates were sensitive to glycopeptides and linezolid; resistance to rifampicin and sulfamethoxazole-trimethoprim was low. MRSA isolates carried more adhesion genes, superantigens were more frequent in MSSA. Panton-Valentine leukocidin was found in 2.3% of the isolates. CONCLUSION This study provides insight into the clonal composition and associated mortality of BSI S. aureus isolates in Hungary. The results suggest that the outcome of the infection is determined by the antibiotic resistance, genotype of the bacterium, and patient-related factors; rather than the virulence factors carried by the bacteria.

中文翻译：

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匈牙利一家三级医院 MRSA 和 MSSA 血流感染的抗生素耐药性、毒力、克隆性和死亡率的特征：一项为期 6 年的回顾性研究。


背景技术由于细菌频繁产生抗生素耐药性、毒素和粘附素，金黄色葡萄球菌血流感染(BSI)导致显着的发病率和死亡率。这些特征在耐甲氧西林金黄色葡萄球菌 (MRSA) 和甲氧西林敏感金黄色葡萄球菌 (MSSA) 以及不同 MRSA 克隆的分离株之间存在显着差异，导致金黄色葡萄球菌菌血症的结果。方法 在本研究中，对 2011 年至 2016 年间从匈牙利布达佩斯 Semmelweis 大学分离的所有 MRSA BSI 分离株和相同数量的匹配 MSSA（总共 306 个分离株）进行了抗生素敏感性、毒力基因、克隆性及其与抗生素敏感性、毒力基因、克隆性及其与30 天全因死亡率。还调查了患者相关变量（例如年龄、性别和合并症）的影响。结果 ST22-MRSA-IV 和 ST5-MRSA-II 是我们研究中最常见的克隆。 SCCmec I 分离株显示出最高的耐药率，SCCmec II 携带最多的毒力基因。尽管不同患者组的合并症率相似，但 SCCmec IV 分离株引起的感染与最高死亡率 (42.2%) 相关。 MRSA 组的 30 天全因死亡率为 39.9%，MSSA 组的全因 30 天死亡率为 30.7%。替考拉宁 MIC 增加与高死亡率相关。 MRSA 对环丙沙星、红霉素和克林霉素的耐药性很常见，而 MSSA 分离株对除多西环素外的所有抗生素都更敏感。所有 MRSA 分离株均对糖肽和利奈唑胺敏感；对利福平和磺胺甲恶唑甲氧苄啶的耐药性较低。 MRSA分离株携带更多粘附基因，MSSA中超抗原更常见。在 2.3% 的分离株中发现了 Panton-Valentine 杀白细胞素。 结论 这项研究深入了解了匈牙利 BSI 金黄色葡萄球菌分离株的克隆组成和相关死亡率。结果表明，感染的结果由抗生素耐药性、细菌基因型和患者相关因素决定；而不是细菌携带的毒力因子。