地塞米松对过氧化氢体外氧化杀伤烟曲霉的影响

目的研究地塞米松对过氧化氢（H2O2）体外杀伤烟曲霉（Aspergillus fumigatus,A.fumigatus）的影响。方法用不同浓度的地塞米松（0 mg/mL,0.02 mg/mL,0.2 mg/mL）处理烟曲霉孢子,按照处理时间不同分为A（0.5 h）,B（2 h）,C（7 h）,D（16 h）4组。用测定H2O2杀伤真菌的标准方法——斑点法分别测定各组烟曲霉孢子对H2O2的氧化杀伤敏感性。结果在H2O2浓度为1.5 mmol/L下,未用地塞米松处理的孢子（阴性对照）氧化杀伤敏感性为5×101（生长良好）。A（0.5 h）组：地塞米松0.02 mg/mL处理后孢子的氧化杀伤敏感性为5×10^3;地塞米松0.2 mg/mL处理后孢子的氧化杀伤敏感性为5×10^4。B（2 h）组：地塞米松0.02 mg/mL和0.2 mg/mL处理后孢子的氧化杀伤敏感性均为5×10^3。C（7 h）和D（16 h）组：不同浓度地塞米松处理后氧化杀伤敏感性与阴性对照没有差别（均为5×10^1）。结论地塞米松使H2O2在体外杀伤烟曲霉的能力增强,这种作用仅发生在地塞米松接触烟曲霉孢子的早期（〈2 h）。

The effects of dexamethasone on hydrogen peroxide oxidative killing of Aspergillus fumigatus in vitro

Objective To study the effects of dexamethasone on hydrogen peroxide （H2O2 ） oxidative killing of Aspergillus fumigatus （A. fumigatus） in vitro. Methods A. fumigatus spores were administered with different concentrations （0 mg/mL,0.02 mg/mL,0.2 mg/mL） of dexamethasone and were divided into four groups （ A ：0.5 h, B ：2 h, C ：7 h, D ： 16 h） according to the treatment time. The H202 oxidative killing assay was performed, using spot test in the four groups. Results With 1.5 mmol/L of H2O2, the oxidative killing susceptibility of A. fumigatus without dexamethasone （ negative control） was 5 × 10^1 （ grow well）. Group A： the oxidative killing susceptibility of A.fumigatus treated with 0. 02 mg/mL of dexamethasone was 5 × 10^3 ; and that with 0.2 mg/mL of dexamethasone was 5 × 10^4. Group B ： the oxidative killing susceptibility of A.fumigatus treated with 0. 02 mg/mL and 0.2 mg/mL of dexamethasone was all 5 × 10^3. Group C and Group D： the oxidative killing susceptibility of A.fumigatus with different concentration of dexamethasone had no difference with that of negative control （5 × 10^1 ）. Conclusions Dexamethasone strenthens the ability of H2O2 to kill A. fumigatus in vitro , which happens only at the early stage （ 〈 2 h） of contacting with A. fumigatus spores.