Although high-performance carbon materials are widely used in surface engineering, with emphasis on carbon nanotubes (CNTs), the application of CNT nanocomposites on medical surfaces is poorly documented. In this study, we aimed to evaluate the antimicrobial and anti-adhesive properties of CNT-based surfaces. For this purpose, a PRISMA-oriented systematic review was conducted based on predefined criteria and 59 studies were selected for the qualitative analysis. Results from the analyzed studies suggest that surfaces containing modified CNTs, and specially CNTs conjugated with different polymers, exhibited strong antimicrobial and anti-adhesive activities. These composites seem to preserve the CNT toxicity to microorganisms and promote CNT-cell interactions, as well as to protect them from nonspecific protein adsorption. However, CNTs cannot yet compete with the conventional strategies to fight biofilms as their toxicity profile on the human body has not been thoroughly addressed. This review can be helpful for the development of new engineered medical surfaces.

In the human fungal pathogen Candida albicans , the CUG codon is translated 97% of the time as serine and 3% of the time as leucine, which potentially originates an array of proteins resulting from the translation of a single gene. Genes encoding cell surface proteins are enriched in CUG codons; thus, CUG mistranslation may influence the interactions of the organism with the host. To investigate this, we compared a C. albicans strain that misincorporates 28% of leucine at CUGs with a wild-type parental strain. The first strain displayed increased adherence to inert and host molecules. In addition, it was less susceptible to phagocytosis by murine macrophages, probably due to reduced exposure of cell surface β-glucans. To prove that these phenotypes occurred due to serine/leucine exchange, the C. albicans adhesin and invasin ALS3 was expressed in Saccharomyces cerevisiae in its two natural isoforms (Als3p-Leu and Als3p-Ser). The cells with heterologous expression of Als3p-Leu showed increased adherence to host substrates and flocculation. We propose that CUG mistranslation has been maintained during the evolution of C. albicans due to its potential to generate cell surface variability, which significantly alters fungus-host interactions. IMPORTANCE The translation of genetic information into proteins is a highly accurate cellular process. In the human fungal pathogen Candida albicans , a unique mistranslation event involving the CUG codon occurs. The CUG codon is mainly translated as serine but can also be translated as leucine. Leucine and serine are two biochemically distinct amino acids, hydrophobic and hydrophilic, respectively. The increased rate of leucine incorporation at CUG decoding triggers C. albicans virulence attributes, such as morphogenesis, phenotypic switching, and adhesion. Here, we show that CUG mistranslation masks the fungal cell wall molecule β-glucan that is normally recognized by the host immune system, delaying its response. Furthermore, we demonstrate that two different proteins of the adhesin Als3 generated by CUG mistranslation confer increased hydrophobicity and adhesion ability on yeast cells. Thus, CUG mistranslation functions as a mechanism to create protein diversity with differential activities, constituting an advantage for a mainly asexual microorganism. This could explain its preservation during evolution.

Biofilms are commonly involved in medical device-related infections. The purpose of this study was to determine the antimicrobial and anti-biofilm activity of polyethyleneimine (PEI) and PEI-based nanoparticles (nanoPEI) against Staphylococcus aureus, Staphylococcus epidermidis, Acinetobacter baumannii and Candida albicans (clinical and ATCC strains), and to evaluate their effect upon biofilm formation on polyurethane (PUR)-like catheters. MICs and minimal lethal concentrations of PEI and nanoPEI were determined according to CLSI microdilution reference protocols. For PEI, the MIC value was 195.31 mg l⁻¹ for all the bacteria and 48.83 mg l⁻¹ for the yeast strains. For nanoPEI, the MIC value was 1250 mg l⁻¹ for all the strains except A. baumannii, for which it was 2500 mg l⁻¹. Biofilm formation was assessed with PUR-like catheter segments and biofilm metabolic activity was quantified by colorimetry with a tetrazolium reduction assay. Plasma membrane integrity and membrane potential were assessed by flow cytometry after staining microbial cells with a membrane-impermeable dye, propidium iodide, and a membrane-potential marker, DiBAC₄(3). PEI inhibited growth of all microbial species; higher concentrations of nanoPEI were needed to inhibit growth of all species. Biofilm formation in the presence of anti-bacterial PEI activity was dose-dependent (except for S. epidermidis) and species-related. NanoPEI at 0.5×MIC and MIC significantly reduced the metabolic activity of biofilms of S. aureus, S. epidermidis and A. baumannii, whereas 2×MIC was required in order to inhibit biofilm metabolic activity.

During the last 30 years the incidence of fungal infections has increased dramatically. While the antifungal therapeutic options available are somewhat reduced, most pathogenic microorganisms have an incredible capacity to mutate and acquire resistance. In addition, multiple drugs are often required concomitantly to manage clinically complex disorders. The combination of antibiotics or other compounds with antifungal drugs, simultaneously or sequentially, is commonly adopted in clinical practice, although without a full knowledge of the consequences. Thus, the role of combined therapy and the effect of antibiotics upon fungal growth promotion needs to be critically evaluated and understood in order to avoid undesirable drug interactions. With this review we intend discuss the studies that report about antibiotics inhibiting fungal growth, as well as studies describing the synergistic effect of the combined therapy, i.e. associations between antibiotics or other compounds with antifungal drugs. Alternative therapeutic protocols for fungal disease could be designed, taking advantage of such drug combinations. Critical revision of previously published data is crucial in order to define future research strategies.

Medical device-associated infections (MDAI) are a critical problem due to the increasing usage of medical devices in the aging population. The inhibition of biofilm formation through the use of probiotics has received attention from the medical field in the last years. However, this sparse knowledge has not been properly reviewed, so that successful strategies for biofilm management can be developed. This study aims to summarize the relevant literature about the effect of probiotics and their metabolites on biofilm formation in medical devices using a PRISMA-oriented (Preferred Reporting Items for Systematic reviews and Meta-Analyses) systematic search and meta-analysis. This approach revealed that the use of probiotics and their products is a promising strategy to hinder biofilm growth by a broad spectrum of pathogenic microorganisms. The meta-analysis showed a pooled effect estimate for the proportion of biofilm reduction of 70% for biosurfactants, 76% for cell-free supernatants (CFS), 77% for probiotic cells and 88% for exopolysaccharides (EPS). This review also highlights the need to properly analyze and report data, as well as the importance of standardizing the in vitro culture conditions to facilitate the comparison between studies. This is essential to increase the predictive value of the studies and translate their findings into clinical applications.

The application of graphene-based materials in medicine has led to significant technological breakthroughs. The remarkable properties of these carbon materials and their potential for functionalization with various molecules and compounds make them highly attractive for numerous medical applications. To enhance their functionality and applicability, extensive research has been conducted on surface modification of graphene (GN) and its derivatives, including modifications with antimicrobials, metals, polymers, and natural compounds. This review aims to discuss recent and relevant studies related to advancements in the formulation of graphene composites, addressing their antimicrobial and/or antibiofilm properties and evaluating their biocompatibility, with a primary focus on their biomedical applications. It was concluded that GN surface modification, particularly with compounds intrinsically active against bacteria (e.g., antimicrobial peptides, silver and copper nanomaterials, and chitosan), has resulted in biomaterials with improved antimicrobial performance. Furthermore, the association of GN materials with non-natural polymers provides composites with increased biocompatibility when interfaced with human tissues, although with slightly lower antimicrobial efficacy. However, it is crucial to highlight that while modified GN materials hold huge potential, their widespread use in the medical field is still undergoing research and development. Comprehensive studies on safety, long-term effects, and stability are essential before their adoption in real-world medical scenarios.