Background: Chronic wounds are frequently associated with biofilms, in which not only bacterial but also fungal pathogens can impair wound healing. Among the most relevant opportunistic pathogens is Staphylococcus aureus; together with Candida albicans, both are part of the human skin microbiome but can also colonize chronic wounds. Interkingdom biofilms formed by these microorganisms have been shown to exacerbate the course of diseases compared to infections caused by either species alone. Methods: To address the limited number of studies examining fungal–bacterial interactions in wound environments, leucocyte-rich human plasma biofilm models (lhBIOMs) inoculated with S. aureus and C. albicans were prepared. The efficacy of the commonly used clinical antiseptics octenidine dihydrochloride/phenoxyethanol (OCT/PE) and polyhexamethylene biguanide (PHMB) was examined using the quantitative suspension method (QSM). In addition, spatial distribution and morphology of the microorganisms within this biofilm model were analyzed by confocal laser scanning microscopy (CLSM). Results: In this study, the presence of S. aureus triggered an increase in the formation of filamentation of C. albicans in contrast to the single-species biofilm. In addition, treatment with the tested antimicrobial agents was effective against C. albicans after repetitive applications and showed a clear reduction against S. aureus. Furthermore, the quantitative analysis of the co-culture revealed increased growth of S. aureus in the control culture compared to the single-species model. Conclusions: These findings highlight the pathogenic relevance of interkingdom biofilms in chronic wounds and emphasize the importance of effective species-independent antimicrobial treatment strategies.

Biodegradable biomaterials are promising candidates for regenerative wound care, yet their performance under infection-driven conditions remains poorly understood. This study evaluated the regenerative efficacy and structural persistence of a silk fibroin membrane and electrospun nonwoven matrix using a human ex vivo full-thickness skin wound model under non-infected and bacterially infected conditions. Complementary in vitro degradation assays assessed matrix durability following exposure to Staphylococcus aureus, Pseudomonas aeruginosa, bacterial culture supernatants and clinically relevant antiseptic solutions. In non-infected wound conditions, both matrices enhanced wound regeneration, resulting in increased re-epithelialization and proliferative activity compared with untreated controls; membrane-treated wounds achieved approximately 95% re-epithelialization after 15 days compared with approximately 20% in untreated controls, indicating accelerated wound closure, whereas nonwoven matrices supported sustained cellular proliferation over time. In contrast, bacterial infection was associated with almost complete absence of re-epithelialization and proliferative activity irrespective of matrix architecture. Matrix persistence was pathogen-dependent. While S. aureus induced moderate degradation, P. aeruginosa caused pronounced structural deterioration in ex vivo and in vitro models. Exposure to P. aeruginosa culture supernatants produced similar effects. These findings demonstrate that regenerative efficacy and material persistence are distinct biomaterial properties that are strongly influenced by the wound microbiological environment and are profoundly compromised under conditions of high bacterial burden.