Long-term impact of molecular epidemiology shifts of methicillin-resistant <i>Staphylococcus aureus</i> on severity and mortality of bloodstream infection

A 2019 nationwide study in Japan revealed the predominant methicillin-resistant Staphylococcus aureus (MRSA) types in bloodstream infections (BSIs) to be sequence type (ST)8-carrying SCC<i>mec</i> type IV (ST8-MRSA-IV) and clonal complex 1-carrying SCC<i>mec</i> type IV (CC1-MRSA-IV). However, detailed patient characteristics and how these MRSA types evolve over time remain largely unknown. In this long-term single-center study, MRSA strains isolated from blood cultures at Nagasaki University Hospital from 2012 to 2019 were sequenced and analyzed. Additionally, we compared the SCC<i>mec</i> types and patient characteristics identified in this study with previous data from our hospital spanning 2003–2007 and 2008–2011. Over this 16-year period, SCC<i>mec</i> type II decreased significantly from 79.2% to 15.5%, while type IV increased from 18.2% to 65.5%. This shift in SCC<i>mec</i> types was associated with notable changes in severity and outcomes; the sequential organ failure assessment (SOFA) score decreased from 5.8 to 3.1; in-hospital mortality declined from 39.8% to 15.5%. In contrast, no significant changes in patient demographics, such as age, sex, or underlying diseases, were observed. Between 2012 and 2019, the major combinations of SCC<i>mec</i> type and sequence type were ST8-MRSA-IV, ST8-MRSA-I, CC1-MRSA-IV, and ST5-MRSA-II. Additionally, ST8-MRSA-IV was divided into CA-MRSA/J, t5071-ST8-MRSA-IV, and USA300-like clone based on the results of molecular analysis. These major combinations showed similar drug resistance patterns, molecular characteristics, and phylogenetic features to those identified in nationwide surveillance. This study highlights the evolving nature of MRSA types in bloodstream infections, correlating with improved patient outcomes over time.

2019年日本一项全国性研究显示，血流感染（bloodstream infections, BSIs）中占主导地位的耐甲氧西林金黄色葡萄球菌（methicillin-resistant Staphylococcus aureus, MRSA）型别为携带葡萄球菌染色体盒mec（staphylococcal chromosomal cassette mec, SCCmec）IV型的序列型8（ST8-MRSA-IV）以及携带SCCmec IV型的克隆复合群1（clonal complex 1, CC1-MRSA-IV）。然而，此类MRSA型别的详细患者特征及其随时间演变的机制，目前仍未被充分阐明。本项长期单中心研究对2012至2019年于长崎大学医院血培养标本中分离的MRSA菌株完成了测序与分析。此外，本研究将本次研究中鉴定的SCCmec型别与患者特征，与本院2003–2007年及2008–2011年的既往数据进行了对比。在这16年的研究周期内，SCCmec II型的占比从79.2%显著下降至15.5%，而SCCmec IV型的占比则从18.2%上升至65.5%。这种SCCmec型别的变迁与患者病情严重程度及预后的显著变化相关：序贯器官衰竭评分（sequential organ failure assessment, SOFA）从5.8降至3.1，住院病死率从39.8%降至15.5%。与之相反，患者的人口统计学特征，如年龄、性别或基础疾病，未观察到显著变化。2012至2019年间，SCCmec型别与序列型的主要组合包括ST8-MRSA-IV、ST8-MRSA-I、CC1-MRSA-IV及ST5-MRSA-II。此外，经分子分析结果验证，ST8-MRSA-IV可分为社区获得性MRSA（community-acquired MRSA, CA-MRSA）/J、t5071-ST8-MRSA-IV以及类USA300克隆株。上述主要组合的耐药谱、分子特征及系统发育特征，与全国监测中鉴定的菌株具有高度相似性。本研究揭示了血流感染相关MRSA型别的动态演变特性，并证实其与患者预后的逐步改善存在显著关联。

搜集汇总

背景与挑战

背景概述

该数据集包含一项关于耐甲氧西林金黄色葡萄球菌（MRSA）分子流行病学变化对血流感染长期影响的单中心研究数据，覆盖2012年至2019年日本医院的菌株测序分析，并与早期数据（2003-2011年）对比。研究发现，SCCmec类型从II型向IV型的转变与患者严重程度（SOFA评分下降）和住院死亡率降低显著相关，同时识别了ST8-MRSA-IV等主要克隆类型及其与全国监测的一致性。