Background: With the antibiotic crisis, the topical antibacterial control including chronic wounds gains increasing importance. However, little is known regarding tolerance development when bacteria face repetitive exposure to the identical antiseptics as commonly found in clinical practice. Materials and Methods: Clinical isolates foremost of chronic wounds were exposed in vitro to dilutions of two antiseptics used for wound therapy: polyhexanide or octenidine. Adaptive response was determined by growth/kill curves, minimal inhibitory concentration (MIC), and whole genome sequencing. Antiseptic/bacteriophage combinations were studied by liquid-infection assays and bacterial plating. Results: Polyhexanide acted stronger against Escherichia coli and Proteus mirabilis while octenidine was more potent against Staphylococcus aureus. Otherwise, the antiseptic efficacy varied across isolates of Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii. Upon repetitive exposure with constant antiseptic concentrations P. aeruginosa and P. mirabilis adaptation was evident by a reduced lag-phase and a twofold increased MIC. Under increasing octenidine concentrations, P. aeruginosa adapted to an eightfold higher dosage with mutations in smvA, opgH, and kinB affecting an efflux pump, alginate and biofilm formation, respectively. S. aureus adapted to a fourfold increase of polyhexanide with a mutation in the multiple peptide resistance factor MprF, also conferring cross-resistance to daptomycin. Antiseptic/bacteriophage combinations enhanced bacterial inhibition and delayed adaptation. Conclusion: Different bacterial species/strains respond unequally to low-level antiseptic concentrations. Bacterial adaptation potential at phenotypic and genotypic levels may indicate the necessity for a more nuanced selection of antiseptics. Bacteriophages represent a promising yet underexplored strategy for supporting antiseptic treatment, which may be particularly beneficial for the management of critical wounds.

In this study, the potential of silk fibroin biomaterials for enhancing wound healing is explored, focusing on their integration into a human 3D ex vivo wound model derived from abdominoplasties. For this purpose, cast silk fibroin membranes and electrospun nonwoven matrices from Bombyx mori silk cocoons were compared to untreated controls over 20 days. Keratinocyte behavior and wound healing were analyzed qualitatively and quantitatively by histomorphometric and immune histochemical methods (HE, Ki67, TUNEL). Findings reveal rapid keratinocyte proliferation on both silk fibroin membrane and nonwoven matrices, along with enhanced infiltration in the matrix, suggesting improved early wound closure. Silk fibroin membranes exhibited a significantly improved early regeneration, followed by nonwoven matrices (p < 0.05) compared to untreated wounds, resulting in the formation of multi-layered epidermal structures with complete regeneration. Overall, the materials demonstrated excellent biocompatibility, supporting cell activity with no signs of increased apoptosis or early degradation. These results underscore silk fibroin’s potential in clinical wound care, particularly in tissue integration and re-epithelialization, offering valuable insights for advanced and—as a result of the electrospinning technique—individual wound care development. Furthermore, the use of an ex vivo wound model appears to be a viable option for pre-clinical testing.

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.