Most manifestations of candidiasis are associated with biofilm formation on biological or inanimate surfaces. Candida albicans biofilms are recalcitrant to treatment with conventional antifungal therapies. Here we report on the activity of caspofungin, a new semisynthetic echinocandin, against C. albicans biofilms. Caspofungin displayed potent in vitro activity against sessile C. albicans cells within biofilms, with MICs at which 50% of the sessile cells were inhibited well within the drug's therapeutic range. Scanning electron microscopy and confocal scanning laser microscopy were used to visualize the effects of caspofungin on preformed C. albicans biofilms, and the results indicated that caspofungin affected the cellular morphology and the metabolic status of cells within the biofilms. The coating of biomaterials with caspofungin had an inhibitory effect on subsequent biofilm development by C. albicans. Together these findings indicate that caspofungin displays potent activity against C. albicans biofilms in vitro and merits further investigation for the treatment of biofilm-associated infections.Biofilms are structured microbial communities with a complex three-dimensional architecture characterized by a network of adherent cells connected by water channels and encapsulated within an extracellular matrix. Biofilms of Candida species play a growing role in human medicine. Indeed, the majority of manifestations of candidiasis at both mucosal and systemic sites are associated in one way or another with the formation of biofilms on inert or biological surfaces (11,14,18). More than their planktonic (free-living) counterparts, cells grown in biofilms can be very recalcitrant to antimicrobial treatment. Our group and others have demonstrated the intrinsic resistance of Candida albicans biofilms to the most commonly used antifungal agents, fluconazole and amphotericin (5,13,23,27,(35)(36)(37)(38).Caspofungin (formerly reported as MK-0991 and L-743,872) is a fungicidal, water-soluble semisynthetic echinocandin that inhibits synthesis of 1,3-␤-D-glucan, a main structural component of the fungal cell wall. Caspofungin has proven to be very effective against different clinically important fungi, especially Candida spp. and Aspergillus spp. (1-3, 9, 15, 30, 31), and it is also active against those Candida isolates displaying high levels of fluconazole resistance (4,8,28,41 , abstr. 854, 2000). Because the fungal cell wall plays critical structural and adhesive roles that are deemed to be important in biofilm formation and development, we hypothesized that this new agent targeting a key step in the fungal cell wall biosynthesis could be effective against C. albicans biofilms. MATERIALS AND METHODSOrganisms and culture conditions. C. albicans 3153A, a well-characterized strain derived from a clinical isolate, was used throughout this study. It was stored on Sabouraud dextrose slopes (BBL, Cockeysville, Md.) at Ϫ70°C. C. albicans 3153A was propagated in yeast extract-peptone-dextrose medium (1% [wt/vol] yeast extract, 2%...

We have examined the in vitro activities of fluconazole, amphotericin B, and caspofungin against Candida albicans biofilms by time-kill methodology. Fluconazole was ineffective against biofilms. Killing of biofilm cells was suboptimal at therapeutic concentrations of amphotericin B. Caspofungin displayed the most effective pharmacokinetic properties, with >99% killing at physiological concentrations.

Candida albicans is an opportunistic pathogenic fungus capable of causing infections in immunocompromised patients. Candidiasis is often associated with the formation of biofilms on the surface of inert or biological materials. Biofilms are structured microbial communities attached to a surface and encased within a matrix of exopolymeric substance (EPS). At present, very little is known about the changes in protein profiles that occur during the transition from the planktonic to the biofilm mode of growth. Here, we report the use of proteomics for the comparative analysis of subcellular fractions obtained from C. albicans biofilm and planktonic cultures, including cell surface-associated proteins and secreted components present in liquid culture supernatants (for planktonic cultures) and EPS (for biofilms). The analysis revealed a high degree of similarity between the protein profiles associated with the planktonic and biofilm extracts, and led to the identification of several differentially expressed protein spots. Among the differentially expressed proteins, there was a preponderance of metabolic enzymes that have been described as cell surface proteins and immunodominant antigens. Proteins found in the biofilm matrix included a few predicted to form part of the secretome, and also many secretion-signal-less proteins. These observations contribute to our understanding of the C. albicans biofilm lifestyle.

Candida dubliniensis is an opportunistic yeast that has been increasingly implicated in oropharyngeal candidiasis (OPC) in human immunodeficiency virus (HIV)-infected patients but may be underreported due to its similarity with Candida albicans. Although most C. dubliniensis isolates are susceptible to fluconazole, the inducibility of azole resistance in vitro has been reported. Thus, the use of fluconazole prophylaxis in the treatment of these patients may have contributed to the increasing rates of isolation of C. dubliniensis. In this study, yeast strains were collected from the oral cavities of HIV-infected patients enrolled in a longitudinal study of OPC. Patients received fluconazole for the suppression or treatment of OPC, and isolates collected at both study entry and end of study were chosen for analysis. Samples were plated on CHROMagar Candida medium for initial isolation and further identified by Southern blot analysis with the species-specific probes Ca3 (for C. albicans) and Cd25 (for C. dubliniensis). Fluconazole MICs were determined by using NCCLS methods. At study entry, susceptible C. albicans isolates were recovered from oral samples in 42 patients who were followed longitudinally (1 to 36 months). C. albicans strains from 12 of these patients developed fluconazole resistance (fluconazole MIC, >64 g/ml). C. dubliniensis was not detected at end of study in any of these patients. Of the remaining 30 patients, eight (27%) demonstrated a replacement of C. albicans by C. dubliniensis when a comparison of isolates obtained at baseline and those from the last culture was done. For the 22 of these 30 patients in whom no switch in species was detected, the fluconazole MICs for initial and end-of-study C. albicans isolates ranged from 0.125 to 2.0 g/ml. For the eight patients in whom a switch to C. dubliniensis was detected, the fluconazole MICs for C. dubliniensis isolates at end of study ranged from 0.25 to 64 g/ml: the fluconazole MICs for isolates from six patients were 0.25 to 2.0 g/ml and those for the other two were 32 and 64 g/ml, respectively. In conclusion, a considerable number of patients initially infected with C. albicans strains that failed to develop fluconazole resistance demonstrated a switch to C. dubliniensis. C. dubliniensis in this setting may be underestimated due to lack of identification and may occur due to the impact of fluconazole on the ecology of oral yeast species.