Han Xiang, Zhang Heng, Mao Yuqi, Ling Wenhao, Ge Lu, Tang Menghua, Sun Yi, Wu Zhiqin
Department of Ophthalmology, Jingzhou Hospital Affiliated to Yangtze University, Jingzhou, 434100, Hubei Province, China.
Health Science Center, Yangtze University, Jingzhou, 434023, Hubei Province, China.
Mycopathologia. 2025 Sep 11;190(5):83. doi: 10.1007/s11046-025-00993-z.
Fungal keratitis (FK), a severe ocular infection caused primarily by Fusarium spp. and Aspergillus spp., remains a major cause of blindness worldwide. Current treatment relies on antifungal agents, though emerging azole resistance in Aspergillus fumigatus complicates therapeutic outcomes.
We isolated a clinical FK strain and assessed its antifungal susceptibility using broth microdilution and E-test methods, followed by sequencing of the cyp51A gene's promoter region and coding sequence (CDS) to identify resistance-associated mutations.
The isolate, confirmed as A. fumigatus (Aftr46-001) via ITS and β-tubulin sequencing, exhibited elevated minimum inhibitory concentrations (MICs) 16 µg/mL for itraconazole (ITC), 32 µg/mL for isavuconazole (ISA), 32 µg/mL for voriconazole (VRC), and 1 µg/mL for posaconazole (POS) by broth microdilution. E-test results revealed an ITR MIC of 12 µg/mL, ISA MIC 32 µg/mL, VRC MIC 32 µg/mL, and POS MIC of 2 µg/mL. The isolate exhibited MICs values at or above the CLSI and EUCAST epidemiological cutoff values (ECVs): 1 µg/mL for ITC, ISA, and VRC according to CLSI (with insufficient data to establish a POS ECV), and 1 µg/mL for ITC and VRC, 2 µg/mL for ISA, and 0.25 µg/mL POS per EUCAST criteria. Genotypic analysis identified a 46-nucleotide tandem repeat in the cyp51A promoter and two nonsynonymous mutations (Y46F, F70L).
This represents the first report of a cyp51A TR46/Y46F/F70L-harboring A. fumigatus strain isolated from FK, with potential agricultural environmental origins, suggesting that this mutation may have become a potential driver of azole-resistant FK in areas with high agricultural exposure, urgently needing to be included in local treatment guidelines and active surveillance systems. The isolate's resistance to all tested azoles underscores the clinical challenge posed by this genotype. Following this combined intervention, the patient's left eye vision improved from counting fingers at 1 m upon admission to a final visual acuity of 0.3, indicating that combined surgery and local high-dose drug delivery can serve as an effective strategy for drug-resistant FK. These findings highlight the importance of monitoring azole-resistant A. fumigatus strains to guide clinical treatment. The global increase in azole drug resistance further highlights the urgency and importance of rapid and accurate pathogen identification and drug resistance testing in the current environment.
真菌性角膜炎（FK）是一种主要由镰刀菌属和曲霉菌属引起的严重眼部感染，仍然是全球失明的主要原因。目前的治疗依赖于抗真菌药物，尽管烟曲霉中出现的唑类耐药性使治疗结果变得复杂。
我们分离出一株临床FK菌株，使用肉汤微量稀释法和E-test方法评估其抗真菌药敏性，随后对cyp51A基因的启动子区域和编码序列（CDS）进行测序，以鉴定耐药相关突变。
通过ITS和β-微管蛋白测序确认该分离株为烟曲霉（Aftr46 - 001），肉汤微量稀释法显示其对伊曲康唑（ITC）的最低抑菌浓度（MIC）升高至16 µg/mL，对艾沙康唑（ISA）为32 µg/mL，对伏立康唑（VRC）为32 µg/mL，对泊沙康唑（POS）为1 µg/mL。E-test结果显示ITR的MIC为12 µg/mL，ISA的MIC为32 µg/mL，VRC的MIC为32 µg/mL，POS的MIC为2 µg/mL。该分离株的MIC值等于或高于CLSI和EUCAST的流行病学临界值（ECV）：根据CLSI，ITC、ISA和VRC的ECV为1 µg/mL（泊沙康唑的ECV数据不足），根据EUCAST标准，ITC和VRC的ECV为1 µg/mL，ISA为2 µg/mL，泊沙康唑为0.25 µg/mL。基因分型分析在cyp51A启动子中鉴定出一个46个核苷酸的串联重复以及两个非同义突变（Y46F、F70L）。
这是首次报道从FK中分离出携带cyp51A TR46/Y46F/F70L的烟曲霉菌株，其可能源自农业环境，表明这种突变可能已成为农业暴露高发地区唑类耐药性FK的潜在驱动因素，迫切需要纳入当地治疗指南和主动监测系统。该分离株对所有测试唑类的耐药性凸显了这种基因型带来的临床挑战。经过这种联合干预，患者左眼视力从入院时1米处数指提高到最终视力0.3，表明联合手术和局部高剂量药物递送可作为耐药性FK的有效策略。这些发现强调了监测唑类耐药烟曲霉菌株以指导临床治疗的重要性。唑类耐药性在全球范围内的增加进一步凸显了在当前环境下快速准确鉴定病原体和进行耐药性检测的紧迫性和重要性。
