Ferreira JA, Carr JH, Starling CE, de Resende MA, Donlan RM
Biofilm formation and the effect of caspofungin on the biofilm structure of Candida spp. bloodstream isolates. [JOURNAL ARTICLE]
Antimicrob Agents Chemother 2009 Jun 22.
Candida biofilms are microbial communities, embedded in a polymeric matrix, growing attached to a surface and are highly recalcitrant to antimicrobial therapy. These biofilms exhibit enhanced resistance against most antifungal agents except echinocandins and lipid formulations of amphotericin B (AMB). In this study, biofilm formation by different Candida species, particularly C. albicans, C. tropicalis, and C. parapsilosis, was evaluated, and the effect of caspofungin (CAS) was assessed using a clinically relevant in vitro model system. CAS displayed in vitro activity against C. albicans and C. tropicalis cells within biofilms. Biofilm formation was evaluated after 48h of antifungal drug exposure and the effects of CAS on preformed Candida species biofilms were visualized using scanning electron microscopy (SEM). Several species-specific differences of the cellular morphologies associated with biofilms were observed. Our results confirmed the presence of paradoxical growth (PG) in C. albicans and C. tropicalis biofilms in the presence of high CAS concentrations. These findings were also confirmed by SEM analysis and associated with the metabolic activity obtained by biofilm susceptibility testing. Importantly, these results suggest that the presence of atypical, enlarged, conical cells could be associated with PG, and with tolerant cells in Candida species biofilm populations. The clinical implications of these findings are still unknown.
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