Emerg Infect Dis. 2023 May;29(5):898-908. doi: 10.3201/eid2905.221421.
Clindamycin and β-lactam antibiotics have been mainstays for treating invasive group A Streptococcus (iGAS) infection, yet such regimens might be limited for strains displaying MLS phenotypes. We investigated 76 iGAS isolates from 66 patients in West Virginia, USA, during 2020-2021. We performed emm typing using Centers for Disease Control and Prevention guidelines and assessed resistance both genotypically and phenotypically. Median patient age was 42 (range 23-86) years. We found 76% of isolates were simultaneously resistant to erythromycin and clindamycin, including all emm92 and emm11 isolates. Macrolide resistance was conferred by the plasmid-borne ermT gene in all emm92 isolates and by chromosomally encoded ermA, ermB, and a single mefA in other emm types. Macrolide-resistant iGAS isolates were typically resistant to tetracycline and aminoglycosides. Vulnerability to infection was associated with socioeconomic status. Our results show a predominance of macrolide-resistant isolates and a shift in emm type distribution compared with historical reports.
克林霉素和β-内酰胺类抗生素一直是治疗侵袭性 A 组链球菌（iGAS）感染的主要药物，但对于表现出 MLS 表型的菌株，这些方案可能受到限制。我们调查了 2020 年至 2021 年期间美国西弗吉尼亚州 66 名患者的 76 株 iGAS 分离株。我们按照疾病控制与预防中心的指南进行 emm 分型，并通过基因和表型评估耐药性。中位患者年龄为 42 岁（范围 23-86 岁）。我们发现 76%的分离株同时对红霉素和克林霉素具有耐药性，包括所有 emm92 和 emm11 分离株。所有 emm92 分离株的大环内酯类耐药性由质粒携带的 ermT 基因赋予，而其他 emm 型的耐药性则由染色体编码的 ermA、ermB 和单个 mefA 赋予。大环内酯类耐药的 iGAS 分离株通常对四环素和氨基糖苷类药物具有耐药性。感染易感性与社会经济地位有关。我们的结果显示，与历史报告相比，大环内酯类耐药分离株占主导地位，emm 型分布发生了变化。
