Effect of peroxynitrite on dormant spores and germlings of Aspergillus fumigatus in vitro.

Peroxynitrite was tested for its effects on the opportunistic pathogenic fungus Aspergillus fumigatus. It did not kill any dormant or swollen (4 h in a glucose-peptone medium) conidia in concentrations up to 6.25 mmol/L and the growth of germlings (after 6 or 9 h) was only slightly inhibited by 5 mmol/L peroxynitrite. The peroxynitrite donor SIN-1 (up to 10 mmol/L, 1 d in buffer) did not kill any conidia but inhibited their germination and growth, depending on the medium. Ten mmol/L SIN-1 in a poor medium was fungistatic and germination was stopped for 20 h. Nine strains of A. fumigatus showed resistance comparable to the model strain, while 6 Candida albicans strains were much more susceptible to both peroxynitrite and its donor. The results indicate that peroxynitrite does not contribute substantially to the antifungal activity of phagocytes against A. fumigatus.