Candida albicans/Staphylococcus aureus Dual-Species Biofilm as a Target for the Combination of Essential Oils and Fluconazole or Mupirocin

Aleksandra Budzyńska,Beata Sadowska,Barbara Różalska,Sylwia Różalska

doi:10.1007/s11046-017-0192-y

Abstract

The effectiveness of essential oils (EOs), fluconazole (FLU) and mupirocin (MUP) used alone or in combination against mono-species and mixed Candida albicans/Staphylococcus aureus biofilms was examined. An experimentally established dual-species biofilm model, verified by fluorescence microscopy and viable cell counting, was used. Selected commercial EOs were tested: geranium, citronella and clove oils, which have been chemically characterized and found to differ in the content of the main components (qualitative and quantitative). As expected, C. albicans and S. aureus biofilms were less susceptible to fluconazole and mupirocin action, respectively, compared to the planktonic counterparts. However, the drug effectiveness in combination with the EOs was significantly improved, giving enhancement of biofilm eradication than caused by the antibiotics alone. Moreover, dual-species biofilm formation was limited by sub-MIC of EOs, and preformed mixed biofilm was eliminated more efficiently by combined action of drugs and EOs.

Highlights

Candida albicans in specific host-dependent conditions is an effective opportunistic organism
The Minimal Biofilm Eradication Concentrations (MBEC) of essential oils (EOs), FLU, MUP used separately or in combination were determined against C. albicans and S. aureus 24-h-old biofilms formed in the 96-well microplates
In other set of experiments, the C. albicans biofilm was exposed to fluconazole, while the S. aureus biofilm was exposed to mupirocin

Summary

Introduction

Candida albicans in specific host-dependent conditions is an effective opportunistic organism. The possibility of the development of polymicrobial biofilms, consisting of both fungi and bacteria, should be considered in pathogenesis of various infections. C. albicans is able to grow together with Staphylococcus aureus, S. epidermidis and Enterococcus sp. In the course of blood-borne infections, with Gardnerella vaginalis during vaginal infections, Pseudomonas aeruginosa in cystic fibrosis and diverse other bacteria or fungi in oral as well as in skin/wound infections [2,3,4,5,6]. Since it is known that C. albicans isolates resistant to azoles emerge often, several approaches to overcome this have been proposed. Successful treatment of drug-resistant S. aureus is a major challenge for medicine. The reports on the increasing resistance to pseudomonic acid (mupirocin)—one of the most potent topical antibiotics used against MSSA and MRSA—are of serious concern and necessitate the search for alternatives [10]

Methods

Results

Conclusion