Diclofenac exhibits synergism with azoles against planktonic cells and biofilms of Candida tropicalis

Abstract

This study aimed to evaluate the effect of diclofenac on minimum inhibitory concentrations of antifungals against planktonic cells and biofilms of Candida tropicalis. Susceptibility testing of planktonic cells was evaluated using the broth microdilution assay and checkerboard method. Biofilm formation by C. tropicalis in the presence of diclofenac, alone or in combination with antifungals, was also evaluated, and scanning electron microscope (SEM) and confocal microscope (CLSM) analyses were performed. Diclofenac showed an MIC of 1024 μg ml⁻¹ against planktonic cells. The MICs of fluconazole and voriconazole against azole-resistant isolates were reduced 8- to 32-fold and 16- to 256-fold, respectively, when in combination with diclofenac. When in combination with fluconazole or voriconazole, diclofenac reduced the antifungal concentration necessary to inhibit C. tropicalis biofilm formation. In conclusion, diclofenac presents synergism with fluconazole and voriconazole against resistant C. tropicalis strains and improves the activity of these azole drugs against biofilm formation.

Keywords:

• Candida tropicalis
• diclofenac
• synergism
• biofilm

Acknowledgements

The authors would like to thank the Central Analítica UFC/CT-INFRA/MCTI-SISNANO/Pro-Equipamentos and CAPES for technical support in obtaining scanning electron microscope images.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by FUNCAP/CAPES (project number 88881.168799/2018-00) and CNPq (Process 306976/2017-0).