分枝横梗霉LYSF001的毒力基因分析与抗真菌药物敏感性评估

Pathogenicity and fungicide resistance of Lichtheimia ramosa LYSF001: analysis of virulence genes and evaluation of sensitivity to fungicides

摘要:

目的 探讨分枝横梗霉菌株LYSF001的致病性及其对常见抗真菌药物的耐药性，为动物真菌感染的诊断与治疗提供实验依据。方法 通过形态学特征和分子生物学技术分离并鉴定菌株；利用PCR技术检测菌株LYSF001的毒力基因，并构建动物感染模型以评估其致病性；采用组织病理学检查、GMS染色及ITS序列扩增技术分析感染动物的肝脏和肾脏病理变化；通过药敏试验评估菌株LYSF001对卡泊芬净、两性霉素B和伊曲康唑的敏感性。结果 菌株LYSF001鉴定为分枝横梗霉；检测出菌株LYSF001携带5个毒力基因，分别为CalA、PKP2、LaeA、Alp2和AspF1；该菌株感染小鼠后造成40%的死亡率，试验小鼠内脏充血，其中肝脏和肾脏的病理变化最为显著，表现为炎症细胞浸润和组织坏死；GMS染色显示心脏、肝脏中存在深色菌丝，ITS序列扩增进一步证实了真菌感染；药敏试验证实菌株LYSF001对两性霉素B及伊曲康唑表现出敏感性，然而该菌株对卡泊芬净存在耐药性。结论 本研究证实分枝横梗霉菌株LYSF001具有较强的致病性，可引发动物严重感染甚至死亡；同时，该菌株对两性霉素B和伊曲康唑敏感，但对卡泊芬净耐药。这为动物真菌感染的诊断与治疗提供了重要的实验依据和技术支持。

Abstract:

Objective To investigate the pathogenicity of Lichtheimia ramosa LYSF001 and ITS resistance to common fungicides, providing experimental evidence for the diagnosis and treatment of fungal infections in animals.Methods The strain was identified by morphological characterization and molecular biology techniques. PCR was employed to detect virulence genes in strain LYSF001, and an animal infection model was established to evaluate the pathogenicity of the strain. Histopathological examination, Grocott’s methenamine silver (GMS) staining, and ITS sequences amplification were employed to analyze pathological changes in the livers and kidneys of infected animals. Additionally, antimicrobial susceptibility tests were conducted to assess the sensitivity of strain LYSF001 to caspofungin, amphotericin B, and itraconazole.Results Strain LYSF001 was identified as L. ramosa. PCR analysis revealed that strain LYSF001 carried five virulence genes (CalA, PKP2, LaeA, Alp2, and AspF1). Animal experiments demonstrated that the strain led to the mortality of 40% and caused visceral hyperemia in mice, with the most significant pathological changes (inflammatory cell infiltration and tissue necrosis) observed in the livers and kidneys. Severe infections led to animal mortality. GMS staining revealed the presence of dark-colored hyphae in the heart and liver, and ITS sequences amplification further confirmed fungal infection. The antimicrobial susceptibility test results indicated that strain LYSF001 was resistant to caspofungin but sensitive to amphotericin B and itraconazole.Conclusion L. ramosa LYSF001 exhibits strong pathogenicity, capable of causing severe infections and even death in animals. Additionally, the strain showed resistance to caspofungin but sensitivity to amphotericin B and itraconazole. The findings provide important experimental evidence and technical support for the diagnosis and treatment of fungal infections in animals.