Wounds of an acute or chronic etiology affect millions of people worldwide, with increasing prevalence every year. Microbial infections are one of the main causes that impair the wound healing process, and Staphylococcus aureus, a commensal member of the skin microbiota, is one of the main causative agents of wound infections. Crucially, a high proportion of these infections are caused by methicillin-resistant Staphylococcus aureus, which, in addition to β-lactams, has acquired resistance to almost all the antibacterial agents used to treat it, limiting therapeutic options. Studies on the antimicrobial and healing activities of extracts, essential oils, or metabolites obtained from native plants have been reported in many countries that have a diverse flora and traditions with the use of medicinal plants for the treatment of wound infections. Due to their great chemical diversity, plants have proven to be promising sources of bioactive molecules for the discovery and development of new drugs or strategies for the treatment of wounds. This review highlights the main herbal preparations that have antimicrobial and healing activities with potential for the treatment of wound infections caused by Staphylococcus aureus.

Candida auris has been found to be a persistent colonizer of human skin and a successful pathogen capable of causing potentially fatal infection, especially in immunocompromised individuals. This fungal species is usually resistant to most antifungal agents and has the ability to form biofilms on different surfaces, representing a significant therapeutic challenge. Herein, the effect of metabolites of Pseudomonas aeruginosa LV strain, alone and combined with biologically synthesized silver nanoparticles (bioAgNP), was evaluated in planktonic and sessile (biofilm) cells of C. auris. First, the minimal inhibitory and fungicidal concentration values of 3.12 and 6.25 μg/mL, respectively, were determined for F4a, a semi-purified bacterial fraction. Fluopsin C and indolin-3-one seem to be the active components of F4a. Like the semi-purified fraction, they showed a time- and dose-dependent fungicidal activity. F4a and bioAgNP caused severe changes in the morphology and ultrastructure of fungal cells. F4a and indolin-3-one combined with bioAgNP exhibited synergistic fungicidal activity against planktonic cells. F4a, alone or combined with bioAgNP, also caused a significant decrease in the number of viable cells within the biofilms. No cytotoxicity to mammalian cells was detected for bacterial metabolites combined with bioAgNP at synergistic concentrations that presented antifungal activity. These results indicate the potential of F4a combined with bioAgNP as a new strategy for controlling C. auris infections.

Plants are a valuable source of bioactive compounds with therapeutic potential. Antibacterials of natural origin represent a promising and sustainable alternative in the fight against bacterial infections. In addition to being effective against bacterial growth, these natural agents may have lower toxicity and fewer side effects, which reinforces their value in the development of new therapeutic strategies. This study reports on the antibacterial effect of eugenol (EUG) and biogenic silver nanoparticles (bioAgNPs) synthesized using the aqueous extract of Trichilia catigua A. Juss. bark, alone or in combination, against planktonic and sessile cells of multidrug-resistant Staphylococcus pseudintermedius, one of the main opportunistic pathogens in dogs. EUG and bioAgNPs showed a dose- and time-dependent bactericidal effect on planktonic cells, interfering with cell membrane integrity. The interaction between EUG and bioAgNPs was classified as synergistic or indifferent for planktonic cells. Except for one isolate, the combination exhibited a synergistic effect for biofilms previously formed on abiotic surfaces for 24 h. Both bioactive compounds promoted morphological and ultrastructural changes in S. pseudintermedius biofilms. All concentrations of EUG and bioAgNPs in synergistic or indifferent combinations showed reduced toxicity to mammalian cells. These findings suggest that the EUG and bioAgNP combination could be a promising strategy for controlling S. pseudintermedius infections.

Introduction: Candida infections represent a major public health concern and the intrinsic and acquired resistance of Candida species to antifungals underscores the need for new therapeutic approaches. In this context, natural products represent a valuable source of bioactive compounds with potential antifungal activity. Methods: The antifungal activity of the Ethyl Acetate Fraction (EAF) of Poincianella pluviosa (DC.) L. P. Queiroz stem bark was evaluated against planktonic Candida spp. by broth microdilution method. The effect of EAF combined with Fluconazole (FLZ) was assessed using the checkerboard assay. The effects of EAF alone and combined with FLZ on Candida albicans morphology and membrane integrity were investigated by scanning electron microscopy and fluorescence microscopy, respectively. The antibiofilm activity of EAF against developing and mature biofilms, as well as its effects on mammalian cell viability, was assessed using tetrazolium-based assays. Results: To our knowledge, this is the first study to investigate the antifungal activity of P. pluviosa stem bark EAF against planktonic and biofilm-associated Candida cells and its interaction with FLZ. EAF exhibited fungistatic activity against all tested strains, including FLZ-resistant isolates, with Minimum Inhibitory Concentrations (MICs) ranging from 31.2 to 500 µg/mL. EAF also reduced the metabolic activity of developing and mature biofilms. The combination of EAF and FLZ showed synergistic activity against most tested strains, reducing the MICs of both compounds. Microscopic analyses revealed reduced metabolic activity in cells treated with EAF alone or combined with FLZ, without detectable changes in cell morphology or cytoplasmic membrane integrity. EAF showed no cytotoxic effects on mammalian cells at the antifungal concentrations tested. Conclusion: These findings highlight the antifungal potential of the stem bark EAF of P. pluviosa, alone and in combination with FLZ, supporting further investigation of EAF as a potential source of bioactive compounds for developing alternative strategies to control Candida infections.