A pre-therapeutic coating for medical devices that prevents the attachment of Candida albicans

Abstract

BackgroundHospital acquired fungal infections are defined as “never events”—medical errors that should never have happened. Systemic Candida albicans infections results in 30–50% mortality rates. Typically, adhesion to abiotic medical devices and implants initiates such infections. Efficient adhesion initiates formation of aggressive biofilms that are difficult to treat. Therefore, inhibitors of adhesion are important for drug development and likely to have a broad spectrum efficacy against many fungal pathogens. In this study we further the development of a small molecule, Filastatin, capable of preventing C. albicans adhesion. We explored the potential of Filastatin as a pre-therapeutic coating of a diverse range of biomaterials.MethodsFilastatin was applied on various biomaterials, specifically bioactive glass (cochlear implants, subcutaneous drug delivery devices and prosthetics); silicone (catheters and other implanted devices) and dental resin (dentures and dental implants). Adhesion to biomaterials was evaluated by direct visualization of wild type C. albicans or a non-adherent mutant edt1 −/− that were stained or fluorescently tagged. Strains grown overnight at 30 °C were harvested, allowed to attach to surfaces for 4 h and washed prior to visualization. The adhesion force of C. albicans cells attached to surfaces treated with Filastatin was measured using Atomic Force Microscopy. Effectiveness of Filastatin was also demonstrated under dynamic conditions using a flow cell bioreactor. The effect of Filastatin under microfluidic flow conditions was quantified using electrochemical impedance spectroscopy. Experiments were typically performed in triplicate.ResultsTreatment with Filastatin significantly inhibited the ability of C. albicans to adhere to bioactive glass (by 99.06%), silicone (by 77.27%), and dental resin (by 60.43%). Atomic force microcopy indicated that treatment with Filastatin decreased the adhesion force of C. albicans from 0.23 to 0.017 nN. Electrochemical Impedance Spectroscopy in a microfluidic device that mimic physiological flow conditions in vivo showed lower impedance for C. albicans when treated with Filastatin as compared to untreated control cells, suggesting decreased attachment. The anti-adhesive properties were maintained when Filastatin was included in the preparation of silicone materials.ConclusionWe demonstrate that Filastatin treated medical devices prevented adhesion of Candida, thereby reducing nosocomial infections.

Contribution of Clinically Derived Mutations in the Gene Encoding the Zinc Cluster Transcription Factor Mrr2 to Fluconazole Antifungal Resistance and CDR1 Expression in Candida albicans

“…Since the publication of the original report first describing them, mutations in MRR2 have been referenced as a clinically relevant mechanism of fluconazole resistance (30)(31)(32). While our results confirm that artificial activation of the Mrr2 ZCF indeed results in CDR1 upregulation and a consequent increase in fluconazole resistance as previously described (14), we were unable to replicate the changes attributed to these mutations in a previous report (28).…”

Advances in Biomaterials for the Prevention and Disruption of Candida Biofilms

“…Adsorption of filastatin on dental resin and silicone showed that Candida cell attachment was reduced on these materials by 62.7 and 79.7%, respectively, compared to uncoated controls. By incorporating filastatin into the silicone matrix during polymerization a 6.5-fold reduction in C. albicans adhesion compared to untreated silicone controls was observed (Vargas-Blanco et al, 2017). Other small molecule biofilm inhibitors specifically interrupt Candida quorum sensing.…”

“…One example, filastatin, a potent small molecule inhibitor of Candida attachment and filamentation was recently identified in a screen of 30,000 compounds (Fazly et al, 2013). Vargas-Blanco et al (2017) found that incubation of C. albicans with various biomaterials in the presence of filastatin can inhibit Candida attachment to these materials. Adsorption of filastatin on dental resin and silicone showed that Candida cell attachment was reduced on these materials by 62.7 and 79.7%, respectively, compared to uncoated controls.…”

“…The majority of biofilm-associated Candida infections arise from cells that colonize the surfaces of implanted medical devices (Coad et al, 2016). These devices range from plastic cochlear implants and subcutaneous drug delivery devices, silicone or polyurethane catheters, and acrylic dental implants, to titanium hip implants, glass-ceramics used in bone repair, metal pacemakers, and polymeric contact lenses among many others (Vargas-Blanco et al, 2017;Cavalheiro and Teixeira, 2018;Devadas et al, 2019). Treatments for these biofilm-associated infections are extremely limited, with only three primary antifungal drug classes (polyenes, azoles, and echinocandins) and a total of 21 United States Food and Drug Administration (FDA) approved antifungal drugs (Butts and Krysan, 2012;McKeny and Zito, 2020), of which only a subset have demonstrated some level of antibiofilm activity.…”

Caenorhabditis elegans as a Model Host to Monitor the Candida Infection Processes

“…For example, Filastatin was discovered using C. elegans as a live host and has been shown to alleviate disease and improve nematode survival to levels comparable to fluconazole [129] using the C. elegans infection model. Furthermore, Filastatin-coated surfaces have been shown to decrease C. albicans adhesion [134].…”