In vitro activity of antifungal combinations against planktonic and sessile cells of Candida albicans isolated from medical devices in an intensive care department

Publication date: Available online 19 July 2018

Source: Journal de Mycologie Médicale

Author(s): H.F.Z. Touil, Z. Boucherit-Otmani, K. Boucherit

Abstract

Background

Invasive fungal infections are an emerging health problem worldwide. They are responsible for a significant rate of morbidity and mortality. Infections caused by Candida albicans involve proliferation of biofilms on biotic or abiotic surface. These adherent communities exhibit characteristics distinct from planktonic cells such as the ability to tolerate high concentrations of antifungal.

Objective

The object of our study was focused on the determination of the susceptibility to amphotericin B, caspofungin, voriconazole and two antifungal combinations (amphotericin B/caspofungin and amphotericin B/voriconazole) of both planktonic and sessile cells of C. albicans, which were isolated from catheters.

Material and methods

The susceptibility of C. albicans to antifungals was determined using the broth microdilution method according to Clinical Laboratory Standards Institute CLSI (2008). A Checkerboard assay was employed to evaluate the efficacy of drugs combinations. Biofilm susceptibility was determined using a metabolic [2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] (XTT) reduction assay.

Results

The minimal inhibitory concentrations of individual antifungal drugs determined against C. albicans biofilms (SMICs) were significantly higher (P < 0.05) than planktonic ones (MICs). They went from 2 to 64 μg/mL for amphotericin B, from 1 to 64 μg/mL for caspofungin and from 2 to 128 μg/mL for voriconazole. The combination of amphotericin B to caspofungin or to voriconazole decreased significantly the MIC values for planctonic (P < 0.0001) and sessile cells (P = 0.0016). Based on Fractional Inhibitory Concentration Index (FICI), no antagonistic interaction was observed.

Conclusion

The obtained results showed that the combination of amphotericin B with either caspofungin or voriconazole can be used as a new strategy for management of systemic mycoses associated to medical devices.