Aung Meiji Soe, Osada Masako, Urushibara Noriko, Kawaguchiya Mitsuyo, Ohashi Nobuhide, Hirose Mina, Ito Masahiko, Yamada Kazuki, Tada Kousuke, Kobayashi Nobumichi
Department of Hygiene, Sapporo Medical University School of Medicine, Hokkaido, Sapporo, Japan.
Master's Program in Midwifery, Tenshi College Graduate School, Sapporo, Japan.
J Glob Antimicrob Resist. 2025 Mar;41:77-87. doi: 10.1016/j.jgar.2024.12.010. Epub 2024 Dec 24.
Staphylococcus aureus (S. aureus) is a major cause of bloodstream infections. The recent epidemiological features and antimicrobial resistance trend were analysed for methicillin-resistant and susceptible S. aureus (MRSA/MSSA) isolates from blood samples in people from northern Japan.
The S. aureus isolates from blood culture were screened by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) and genotyped by the schemes of multilocus sequence typing (MLST), coa, agr, spa, and SCCmec types. Antimicrobial resistance genes and virulence factors were detected by multiplex/uniplex polymerase chain reaction (PCR). Antimicrobial susceptibility was examined using a broth microdilution test.
A total of 301 isolates (163 MRSA and 138 MSSA) were isolated from bloodstream infections in 2023 (from April to December). The MRSA isolates were classified into three groups, that is, clonal complexes (CC)1-SCCmec-IV (CC1-IV) (52%), CC5-II (36%), and CC8-IV (12%). The prevalence of CC1 was significantly higher than those in our previous studies (2017-2021). Four CC8-IVa isolates with PVL genes on ΦSa2usa were considered to be the USA300 clone (sequence type [ST]8/spa-t008/coa IIIa/agr I) or its variants that were genotyped as those closely related to ST8/t008 or lacking arginine catabolic mobile element (ACME). In contrast, MSSA was genetically highly divergent and classified into 22 STs, with CC1 (ST1 and ST188) being the most common (25%). It was notable that 29 MSSA isolates (21%) were classified into livestock-associated (LA) genotypes, ST20, ST97, and CC398 (ST398 and ST291). Genetic characterization of the CC398 isolates suggested that these belong to human-adapted MSSA clones.
The present study revealed the increasing trend of CC1 MRSA surpassing CC5, and the emergence of MSSA representing human-adapted CC398, and LA types ST97 and ST20 from bloodstream infections in people in Japan. © 2024 The Author(s). Published by Elsevier Ltd on behalf of International Society for Antimicrobial Chemotherapy.
金黄色葡萄球菌是血流感染的主要原因。分析了日本北部人群血液样本中耐甲氧西林和敏感金黄色葡萄球菌（MRSA/MSSA）分离株的近期流行病学特征及抗菌药物耐药趋势。
通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）对血培养中的金黄色葡萄球菌分离株进行筛选，并采用多位点序列分型（MLST）、coa、agr、spa和SCCmec分型方案进行基因分型。通过多重/单重聚合酶链反应（PCR）检测抗菌药物耐药基因和毒力因子。采用肉汤微量稀释法检测抗菌药物敏感性。
2023年（4月至12月）从血流感染中分离出301株菌株（163株MRSA和138株MSSA）。MRSA分离株分为三组，即克隆复合体（CC）1-SCCmec-IV（CC1-IV）（52%）、CC5-II（36%）和CC8-IV（12%）。CC1的流行率显著高于我们之前的研究（2017 - 2021年）。4株携带ΦSa2usa上PVL基因的CC8-IVa分离株被认为是USA300克隆（序列类型[ST]8/spa-t008/coa IIIa/agr I）或其变体，基因分型与ST8/t008密切相关或缺乏精氨酸分解代谢移动元件（ACME）。相比之下，MSSA在基因上高度分散，分为22个ST型，其中CC1（ST1和ST188）最为常见（25%）。值得注意的是，29株MSSA分离株（21%）被分类为与家畜相关（LA）的基因型，即ST20、ST97和CC398（ST398和ST291）。CC398分离株的基因特征表明它们属于适应人类的MSSA克隆。
本研究揭示了日本人群血流感染中CC1 MRSA超过CC5的上升趋势，以及代表适应人类的CC398、LA型ST97和ST20的MSSA的出现。© 2024作者。由爱思唯尔有限公司代表国际抗菌化疗协会出版。
