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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 important minerals like zinc that these fungi need to survive. Testing showed nitroxoline was very effective against these fungi, even against strains that had developed resistance to modern antifungal drugs. This suggests nitroxoline could potentially be repurposed as a new treatment option for serious fungal infections.

Background

Nitroxoline is an old antibiotic approved for uncomplicated urinary tract infections that acts through chelation of bivalent cations like zinc. Aspergillus species metabolism is highly dependent on zinc in several metabolic pathways. Rising azole resistance in Aspergillus infections necessitates new therapeutic alternatives.

Objective

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

Results

Nitroxoline demonstrated overall MICs ranging from 0.125 to 1 mg/L with MIC 50/90 of 0.5 mg/L against all Aspergillus isolates tested, including the two azole-resistant strains. MIC values were similar to or lower than previously reported values for other filamentous fungi and well below the EUCAST breakpoint of 16 mg/L established for E. coli.

Conclusion

Nitroxoline demonstrates excellent in vitro activity against Aspergillus species, including azole-resistant isolates. Further studies are needed to evaluate in vivo efficacy, pharmacokinetic distribution to tissues, and the mechanism of action in Aspergillus species.
  • Published in:Mycoses,
  • Study Type:In Vitro Susceptibility Study,
  • Source: 10.1111/myc.70131; PMID: 41243873
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