Superoxide Dismutases Are Involved in Candida albicans Biofilm Persistence against Miconazole

• Published in: Antimicrobial Agents and Chemotherapy 2011-09, Vol.55 (9), p.4033-4037
• Main Authors: Bink, Anna, Vandenbosch, Davy, Coenye, Tom, Nelis, Hans, Cammue, Bruno P. A, Thevissen, Karin
• Format: Article
• Language: English
• Subjects: antibiotic resistance; Antibiotics. Antiinfectious agents. Antiparasitic agents; Antifungal Agents; Antifungal Agents - pharmacology; biofilm; Biofilms; Biofilms - drug effects; Biological and medical sciences; Candida albicans; Candida albicans - drug effects; Candida albicans - enzymology; Candida albicans - metabolism; Ditiocarb - pharmacology; Drug Resistance, Fungal - genetics; enzyme inhibitors; Fungal Proteins; Fungal Proteins - antagonists & inhibitors; Fungal Proteins - genetics; Fungal Proteins - metabolism; genes; Mechanisms of Resistance; Medical sciences; Miconazole; Miconazole - pharmacology; Microbial Sensitivity Tests; mutants; Pharmacology. Drug treatments; reactive oxygen species; Reactive Oxygen Species - metabolism; Superoxide Dismutase; Superoxide Dismutase - antagonists & inhibitors; Superoxide Dismutase - genetics; Superoxide Dismutase - metabolism; thiocarbamates
• ISSN: 0066-4804; 1098-6596
• DOI: 10.1128/AAC.00280-11

We investigated the cellular mechanisms responsible for the occurrence of miconazole-tolerant persisters in Candida albicans biofilms. Miconazole induced about 30% killing of sessile C. albicans cells at 75 µM. The fraction of miconazole-tolerant persisters, i.e., cells that can survive high doses of miconazole (0.6 to 2.4 mM), in these biofilms was 1 to 2%. Since miconazole induces reactive oxygen species (ROS) in sessile C. albicans cells, we focused on a role for superoxide dismutases (Sods) in persistence and found the expression of Sod-encoding genes in sessile C. albicans cells induced by miconazole compared to the expression levels in untreated sessile C. albicans cells. Moreover, addition of the superoxide dismutase inhibitor N,N'-diethyldithiocarbamate (DDC) to C. albicans biofilms resulted in an 18-fold reduction of the miconazole-tolerant persister fraction and in increased endogenous ROS levels in these cells. Treatment of biofilms of C. albicans clinical isolates with DDC resulted in an 18-fold to more than 200-fold reduction of their miconazole-tolerant persister fraction. To further confirm the important role for Sods in C. albicans biofilm persistence, we used a Δsod4 Δsod5 mutant lacking Sods 4 and 5. Biofilms of the Δsod4 Δsod5 mutant contained at least 3-fold less of the miconazole-tolerant persisters and had increased ROS levels compared to biofilms of the isogenic wild type (WT). In conclusion, the occurrence of miconazole-tolerant persisters in C. albicans biofilms is linked to the ROS-detoxifying activity of Sods. Moreover, Sod inhibitors can be used to potentiate the activity of miconazole against C. albicans biofilms.