Department of Laboratory Medicine, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China.
Graduate School, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
J Antimicrob Chemother. 2024 Jan 3;79(1):128-133. doi: 10.1093/jac/dkad356.
We explored the epidemiological and molecular characteristics of Candida parapsilosis sensu stricto isolates in China, and their mechanisms of azole resistance.
Azole susceptibilities of 2318 non-duplicate isolates were determined using CLSI broth microdilution. Isolates were genotyped by a microsatellite typing method. Molecular resistance mechanisms were also studied and functionally validated by CRISPR/Cas9-based genetic alterations.
Fluconazole resistance occurred in 2.4% (n = 56) of isolates, and these isolates showed a higher frequency of distribution in ICU inpatients compared with susceptible isolates (48.2%, n = 27/56 versus 27.8%, 613/2208; P = 0.019). Microsatellite-genotyping analysis yielded 29 genotypes among 56 fluconazole-resistant isolates, of which 10 genotypes, including 37 isolates, belonged to clusters, persisting and transmitting in Chinese hospitals for 1-29 months. Clusters harbouring Erg11Y132F (5/10; 50%) were predominant in China. Among these, the second most dominant cluster MT07, including seven isolates, characteristically harbouring Erg11Y132F and Mrr1Q625K, lent its carriage to being one of the strongest associations with cross-resistance and high MICs of fluconazole (>256 mg/L) and voriconazole (2-8 mg/L), causing transmission across two hospitals. Among mutations tested, Mrr1Q625K led to the highest-level increase of fluconazole MIC (32-fold), while mutations located within or near the predicted transcription factor domain of Tac1 (D440Y, T492M and L518F) conferred cross-resistance to azoles.
This study is the first Chinese report of persistence and transmissions of multiple fluconazole-resistant C. parapsilosis sensu stricto clones harbouring Erg11Y132F, and the first demonstration of the mutations Erg11G307A, Mrr1Q625K, Tac1L263S, Tac1D440Y and Tac1T492M as conferring resistance to azoles.
我们探索了中国严格意义上近平滑念珠菌分离株的流行病学和分子特征及其唑类耐药机制。
采用 CLSI 肉汤微量稀释法测定 2318 份非重复分离株的唑类药敏性。采用微卫星分型方法对分离株进行基因分型。还通过基于 CRISPR/Cas9 的遗传改变研究和功能验证了分子耐药机制。
氟康唑耐药发生在 2.4%（n=56）的分离株中，与敏感分离株相比，这些分离株在 ICU 住院患者中的分布频率更高（48.2%，n=27/56 比 27.8%，613/2208；P=0.019）。56 株氟康唑耐药分离株的微卫星基因分型分析产生了 29 种基因型，其中 10 种基因型，包括 37 株，属于集群，在中国医院持续传播 1-29 个月。中国以含有 Erg11Y132F（5/10；50%）的簇为主。其中，第二大优势簇 MT07，包括 7 株，特征性地含有 Erg11Y132F 和 Mrr1Q625K，使其与交叉耐药和氟康唑（>256mg/L）和伏立康唑（2-8mg/L）高 MIC 相关联，并导致两家医院之间的传播。在测试的突变中，Mrr1Q625K 导致氟康唑 MIC 升高 32 倍，而位于 Tac1 预测转录因子结构域内或附近的突变（D440Y、T492M 和 L518F）导致唑类交叉耐药。
本研究是中国首例关于含有 Erg11Y132F 的多个耐氟康唑近平滑念珠菌严格意义上的克隆体的持续性和传播的报告，也是首次证明突变 Erg11G307A、Mrr1Q625K、Tac1L263S、Tac1D440Y 和 Tac1T492M 赋予唑类耐药性。
