The sphinganine C4-hydroxylase FgSur2 regulates sensitivity to azole antifungal agents and virulence of Fusarium graminearum

Lipid rafts consisting of ergosterol and sphingolipids in the lipid membrane of cells play important roles in various cellular processes. However, the functions of sphingolipids and their synthetic genes in phytopathogenic fungi have not been well understood yet. In this study, we conducted genome-wide searches and carried out systematic gene deletion analysis of the sphingolipid synthesis pathway in Fusarium graminearum, a causal agent of Fusarium head blight of wheat and other cereal crops worldwide. Mycelial growth assays showed that deletion of FgBAR1, FgLAC1, FgSUR2 or FgSCS7 resulted in markedly reduced hyphal growth. Fungicide sensitivity tests showed that the sphinganine C4-hydroxylase gene FgSUR2 deletion mutant (ΔFgSUR2) exhibited significantly increased susceptibility to azole fungicides. In addition, this mutant displayed a remarkable increase in cell membrane permeability. Importantly, ΔFgSUR2 was defective in deoxynivalenol (DON) toxisome formation, leading to dramatically decreased DON biosynthesis. Moreover, the deletion of FgSUR2 resulted in dramatically decreased virulence of the pathogen on host plants. Taken together, these results indicate that FgSUR2 plays an important role in regulating the susceptibility to azoles and virulence of F. graminearum.

Bleeding Risk Following Systemic Fluconazole or Topical Azoles in Patients with Atrial Fibrillation on Apixaban, Rivaroxaban, or Dabigatran

BACKGROUND

Bleeding safety in relation to use of systemic fluconazole and topical azoles among patients with atrial fibrillation treated with apixaban, rivaroxaban, or dabigatran is insufficiently explored, despite clinical relevance and several reports suggesting associations.

METHODS

Using nationwide Danish registers, we identified patients with atrial fibrillation initiated on apixaban, rivaroxaban, or dabigatran from 2012-2018. We investigated associations between bleeding incidents and systemic fluconazole or topical azole treatment using a case-crossover design with 30-day exposure windows and reported odds ratios (OR) with 95% confidence intervals (CI).

RESULTS

We included 32,340 (36%), 32,409 (36%), and 24,940 (28%) patients initiated on apixaban, rivaroxaban, and dabigatran, respectively. Patients on apixaban were older (median age: 77 years; interquartile range [IQR] 70-84) compared with rivaroxaban users (median age: 75 years; IQR 68-82) and patients on dabigatran (median age: 73 years; IQR 66-80). Apixaban users had a significantly increased risk of bleeding following exposure to systemic fluconazole: odds ratio (OR) 3.5; 95% confidence interval (CI), 1.4-10.6. No increased risk was found among rivaroxaban and dabigatran users: ORs of 0.9 (95% CI, 0.2-3.0) and 1.7 (95% CI, 0.5-5.6), respectively. As to bleeding risk pertaining to topical azole exposure among apixaban, rivaroxaban, and dabigatran users, no association was found, with corresponding ORs of 0.8 (95% CI, 0.5-1.3); 1.3 (95% CI, 0.9-2.1); and 1.2 (95% CI 0.8-1.8), respectively.

CONCLUSION

In patients with atrial fibrillation on either apixaban, rivaroxaban, or dabigatran, an association between an elevated bleeding risk and use of systemic fluconazole was found among patients on apixaban. We found no increased risk of bleeding following co-exposure to topical azoles.

Synergistic activity between Echinophora platyloba DC ethanolic extract and azole drugs against clinical isolates of Candida albicans from women suffering chronic recurrent vaginitis

OBJECTIVE

Candida albicans is one of the main causes of vaginitis, especially in women with recurrent episodes. The appearance of drug resistant C. albicans and adverse effects of chemical agents have raised interest in Echinophora platyloba as one of four native species in Traditional Persian-Iranian medicine.

MATERIALS AND METHODS

This study evaluates the antifungal activity of ethanolic extract from dried aerial parts of E. platyloba against 27 clinical isolates of C. albicans from women suffering chronic recurrent vaginitis by micro-broth dilution assay. The synergistic effect of azole drugs and E. platyloba ethanolic extract were also determined by disc diffusion method after determining the MIC90.

RESULTS

The results of this study showed a potent synergistic effect of E. platyloba ethanolic extract and itraconazole (P<0.01) and fluconazole (P<0.001) but an antagonistic effect between E. platyloba ethanolic extract and clotrimazole and miconazole against clinical isolates of C. albicans.

CONCLUSION

These results must be confirmed by clinical application and by further clinical studies.