硝酸银与三种抗真菌药物体外抗眼部致病真菌活性的对比实验研究

Comparison of the activities of silver nitrate with those of three antifungal agents against ocular pathogenic fungi in vitro

目的探讨硝酸银与氟康唑、酮康唑及两性霉素B对眼部致病真菌的体外抗菌活性。方法实验研究。参照美国临床实验室标准化委员会（NCCLS）制定的M38-A方案，用微量液基稀释法研究硝酸银对260株（15属29种）眼部分离真菌的体外抗菌活性，并与抗真菌药物氟康唑、酮康唑及两性霉素B进行对比研究。实验药物浓度范围分别为硝酸银、酮康唑及两性霉素B0．031～16．000mg／L，氟康唑0．5～256．0mg／L。硝酸银和两性霉素B的最低抑菌浓度（MIC）为100％的真菌生长抑制，氟康唑和酮康唑的MIC为75％的真菌生长抑制。结果硝酸银、氟康唑、酮康唑及两性霉素B对镰刀菌属抑制90％菌株的最低抑菌浓度（MIC90）分别为2．000、512．000、32．000及2．000mg／L；对曲霉菌属的MIC90分别为1．000、256．000、2．000及2．000mg／L；对互隔交链孢霉的MIC90分别为2．000、128．000、4．000及2．000mg／L；对新月弯孢霉的MIC90分别为2．000、4．000、0．125及0．500mg／L；对罕见眼部致病菌的MIC90分别为1．000、256．000、1．000及1．000mg／L。硝酸银对92．9％曲霉菌的MIC≤1．0mg／L，对96．3％镰刀菌的MIC≤2．0mg／L。镰刀菌属和曲霉菌属对氟康唑的耐药率分别为95．6％和90．8％，对两性霉素B的耐药率分别为44．1％和42．9％；镰刀菌属对酮康唑的耐药率为66．2％。硝酸银对氟康唑、酮康唑及两性霉素B耐药的曲霉菌属和氟康唑及酮康唑耐药的镰刀菌属有显著的体外抗菌活性。结论硝酸银对眼部分离真菌有较强的广谱体外抗菌活性，该药适当的浓度、眼用剂型及给药方法将可能对治疗真菌性角膜炎具有临床意义。

Objective To investigate antifungal activity of silver nitrate compared with fluconazole, ketoconazole and amphotericin B against ocular pathogenic fungi in vitro. Methods It was an experimental study. Susceptibility tests were performed against 260 isolates （15 genera and 29 species ）of ocular pathogenic fungi by broth dilution antifungal susceptibility testing of filamentous fungi （M38-A） approved by National Committee for Clinical Laboratory Standards （NCCLS）. Final concentrations ranged from 0. 031 to 16. 000 mg/L for silver nitrate, ketoconazolc and amphotericin B, from 0. 5-256. 0 mg/L for flueonazole. Minimum inhibitory concentration （MIC） was defined as the lowest drug concentration that showed absence of growth or complete growth inhibition （100%）. The end points were determined as 100% growth inhibition for silver nitrate and amphoteriein B, and ≥ 75% growth inhibition for ketoconazole and fluconazole. Results The MICs at which 90% of isolates were inhibited （MIC90） of silver nitrat, ketoconazole, amphotericin B and fluconazole were 2. 000, 512. 000, 32. 000 ancl 2. 000 mg/L for Fusarium species, respectively; 1. 000, 256. 000, 2. 000 and 2. 000 mg/L for AspergiUus species, respectively; 2. 000, 128. 000, 4. 000 and 2. 000 mg/L for Alternaria alternat, respectively; 2. 000, 4. 000,0. 125 and 0. 500 mg/L for Curvularia lunata, respectively ; and 1. 000, 256. 000, 1. 000 and 1. 000 mg/L for unusual ocular pathogens, respectively. Silver nitrate was highly active against Aspergillus species （92. 9% susceptible at a MIC of ≤1.0 mg/L ） and Fusarium species （96. 3% susceptible at a MIC of ≤2. 0 mg/L）. 95.6% of Fusarium species and 90. 8% of Aspergillus species exhibited resistance to fluconazole, 44. 1% of Fusarium species and 42. 9% of Aspergillus species exhibited resistance to amphotericin B, 66. 2% of Fusarium species exhibited resistance to ketoconazole. The activity of silver nitrate against the fluconazole- resistant, ketoconazole-resistant and amphotericin B-resistant strains was high. Conclusion Silver nitrate has promising activity against a wide variety of ocular pathogenic fungi in vitro, and may have a role in future studies of antifungal eye drops and treating fungal keratitis.