Suzuki Katsunori, Saito Mitsumasa, Hanaki Hideaki
Division of Infection Control and Prevention, University of Occupational and Environmental Health, Japan.
Department of Microbiology, School of Medicine, University of Occupational and Environmental Health, Japan.
J Infect Chemother. 2023 May;29(5):481-484. doi: 10.1016/j.jiac.2023.01.019. Epub 2023 Feb 1.
Methicillin-resistant Staphylococcus aureus (MRSA) infection is one of the most difficult infections we have to treat. Linezolid is one of the effective treatment options for refractory MRSA infections. There are cases where we are forced to use long-term linezolid treatment for refractory MRSA infections.
To discuss the evolution of Linezolid resistance factors in clinical isolates of MRSA.
We investigated 16 MRSA isolated from a patient treated with linezolid for a long period of 75 days. We performed antibiotic susceptibility test, 23S rRNA genes sequencing analysis, Pulsed-field gel electrophoresis.
MRSA isolates were susceptible to linezolid before the start of treatment, but became less susceptible by prolonged treatment. The 23S rRNA sequencing analysis of linezolid-resistant strains that appeared 17 days after the start of treatment with linezolid revealed that all resistant MRSA had the G2576T substitution (Escherichia coli 23S rRNA gene number). The number of copies of this mutation increased with the use of linezolid.
Long-term use of linezolid in a patient or reuse of linezolid in a patient who has been previously treated with linezolid can lead to the emerging of linezolid-resistant MRSA in the host.
耐甲氧西林金黄色葡萄球菌（MRSA）感染是我们必须治疗的最棘手的感染之一。利奈唑胺是难治性MRSA感染的有效治疗选择之一。在某些情况下，我们不得不对难治性MRSA感染使用长期利奈唑胺治疗。
探讨MRSA临床分离株中利奈唑胺耐药因子的演变。
我们调查了从一名接受了75天长期利奈唑胺治疗的患者身上分离出的16株MRSA。我们进行了药敏试验、23S rRNA基因测序分析、脉冲场凝胶电泳。
MRSA分离株在治疗开始前对利奈唑胺敏感，但随着治疗时间延长敏感性降低。对利奈唑胺治疗开始17天后出现的耐利奈唑胺菌株进行的23S rRNA测序分析显示，所有耐药MRSA均有G2576T替换（大肠杆菌23S rRNA基因编号）。这种突变的拷贝数随着利奈唑胺的使用而增加。
在患者中长期使用利奈唑胺或在先前接受过利奈唑胺治疗的患者中再次使用利奈唑胺可导致宿主中出现耐利奈唑胺的MRSA。
