Difference in susceptibility to hydrogen peroxide (H2O2) between Aspergillus fumigatus and Fusarium solani

Abstract number: P1354

Dotis J., Simitsopoulou M., Chatzimoschou A., Walsh T.J., Roilides E.

Objectives:A. fumigatus and F. solani cause life-threatening infections in immunocompromised patients. Phagocytes, particularly neutrophils and monocytes/macrophages, constitute the main innate host defences against these fungal pathogens. The oxidative antifungal pathway of NADPH oxidase-catalyzed superoxide anion (O2) production leading to hydrogen peroxide (H2O2) formation is considered critical for the phagocyte-induced hyphal damage. We previously found that F. solani hyphae are more resistant to phagocyte-induced hyphal damage than are hyphae of A. fumigatus [CMI 2005, 11(S2): 364]. Therefore, we attempted to assess the susceptibility of A. fumigatus and F. solani hyphae to the antifungal activity of H2O2.

Methods: Suspensions of the two fungi containing 105 conidia per ml in YNB were incubated in 96-well plates at 37°C for 16–18 h to become hyphae. They were then incubated with 0, 50, 100 and 200 mM H2O2 at room temperature for 10 min. Each hyphal suspension was then washed with H2O twice before adding 150 microliters of a solution containing 0.25 mg/ml XTT plus 40 mg/l coenzyme Q. After incubation at 37°C with 5% CO2 for 30 min, H2O2-induced hyphal damage was colorimetrically assessed as reduction in metabolic activity of hyphae. ANOVA with Dunnett test was used for analysis (n = 36).

Results: H2O2 induced a concentration-dependent hyphal damage on A. fumigatus (p < 0.001). H2O2 induced a non concentration-dependent hyphal damage on F. solani. The hyphal damage induced by 100 mM H2O2 on A. fumigatus was higher than that induced on F. solani (72.7% vs. 53.2%, p = 0.048). At 200 mM, hyphal damage induced by H2O2 on A. fumigatus was 85.0% as compared to 67.1% for F. solani (p = 0.005). Hyphal damage induced by H2O2 at a concentration of 50 mM on A. fumigatus and F. solani was 47.1% and 42.9%, respectively (p=ns).

Conclusion:F. solani hyphae are more resistant than A. fumigatus hyphae to H2O2, a key antifungal component of the oxidative phagocytic pathway. This finding suggests that the activities of soluble mediators of the innate immune response against medically important filamentous fungi are fungal species-dependent and may contribute to differences in susceptibility of these two pathogens to host defence.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Location: Barcelona, Spain
Presentation type:
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