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In Vitro Activity of Nitroxoline (5-Nitro-8-Hydroxyquinoline) Against Aspergillus Species

Summary

Researchers tested an old antibiotic called nitroxoline against dangerous fungal infections caused by Aspergillus species. The drug works by removing essential zinc that the fungus needs to survive. The study found that nitroxoline was highly effective against all tested fungal strains, including those resistant to modern antifungal drugs, suggesting it could be a promising alternative treatment for serious fungal infections.

Background

Nitroxoline is an old antibiotic approved for treating uncomplicated urinary tract infections that works by chelating bivalent cations like zinc. Zinc plays a central role in Aspergillus metabolism, suggesting potential antifungal activity. Rising azole resistance in Aspergillus species necessitates exploration of alternative therapeutic agents.

Objective

To evaluate the in vitro antifungal activity of nitroxoline against clinically relevant Aspergillus species, including azole-resistant strains, using broth microdilution susceptibility testing.

Results

Nitroxoline demonstrated excellent in vitro activity against all tested Aspergillus isolates with overall MIC50/90 of 0.5 mg/L (range 0.125-1 mg/L). Activity was observed against both susceptible and azole-resistant isolates. MIC values were well below the EUCAST breakpoint of 16 mg/L established for E. coli in urinary tract infections.

Conclusion

Nitroxoline demonstrates excellent in vitro activity against Aspergillus species, including azole-resistant strains. These findings support further investigation of nitroxoline as a potential repurposed drug for aspergillosis treatment, though larger isolate sets and in vivo studies are necessary to confirm clinical utility.
  • Published in:Mycoses,
  • Study Type:In Vitro Susceptibility Study,
  • Source: PMID: 41243873, DOI: 10.1111/myc.70131
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