Candida albicans is a common cause of opportunistic mycoses worldwide and a major contributor in wound infections. The purpose of this study was to establish a fungal wound model and analyze the effects of a common antifungal agent against the proliferation of three C. albicans strains. Second degree burns were created, and then inoculated with one of three different C. albicans ATCC strains: 10261 reference strain, 64550 fluconazole resistant and 26310 fluconazole sensitive. After fungal inoculation, every wound was covered with dressings for 4 h to allow fungal colonization on every wound bed. After 4 h, the dressings were removed, and each wound was treated either once or twice daily with a topical terbinafine hydrochloride or left untreated. On days 2, 4 and 7 post inoculation, three wounds from each treatment group were scrub cultured and quantified. On day 2, wounds infected with the sensitive strains 26310 and 10261 and treated twice showed a significant reduction when compared against those infected wounds receiving once daily treatment. On day 4, wounds which were infected with C. albicans fluconazole sensitive (ATCC 26310) showed a significant reduction in fungal cell counts with treatment applied twice daily. A significant reduction in the colony counts was exhibited in all three strains at the seventh day with active as compared to the non-treated wounds. Twice daily treatment resulted in a lower fungal count than once daily treatment. Neither treatment was able to entirely eradicate C. albicans during the duration of this study. Establishing a reliable fungal wound model will help in the translational goal of identifying new antifungal that could be used clinically by wound care providers.

A variety of wound matrix materials that are designed to help heal both acute and chronic wounds are currently available. Because wounds often encounter opportunistic microbes that can delay healing, the effectiveness of these materials is often suboptimal, resulting in delayed or compromised wound healing. The importance of reducing and controlling wound microbes is well recognised and there are several antimicrobial options available to address this unmet clinical need. This study compares the antimicrobial and wound healing capabilities, both in vivo and in vitro against methicillin‐resistant Staphylococcus aureus (MRSA) USA 300, for the following compounds: Collagen Wound Matrix‐Anti Microbial (CWM‐AM); Collagen Wound Matrix‐Anti Microbial XT (CWM‐AM XT); Antimicrobial Hydrofiber Wound Dressing (AHWD); Dermal Scaffold with Silver (DRSAg); Collagen Extracellular Matrix (CEM); Collagen Wound Matrix (CWM); Matrix Wound Dressing with Silver (MWDAg); Cadexomer Iodine Gel (CIG); Triple Antibiotic Ointment (TAO); and Antimicrobial Wound Gel (AWG). For the in vitro zone of inhibition assay, AWG and CIG had the largest diffused areas, followed by CWM‐AM and CWM‐AM XT. Furthermore, CWM‐AM, CWM‐AM XT, AWG, and CIG exhibited a persistent antimicrobial activity for up to 10 days after incubation. However, in the cytotoxicity studies performed using human fibroblasts, CWM‐AM and CWM‐AM XT had no detrimental effects in cell proliferation and viability, while AWG and CIG were cytotoxic and prohibitive for cell proliferation. Treatments were then assessed for microbiology and wound healing efficacy using an in vivo porcine deep reticular dermal wound model. CWM‐AM XT displayed the greatest in vivo antimicrobial activity against MRSA USA300 and expedited the reepithelialisation at a faster rate than other treatment groups. This study shows that a novel collagen matrix containing an antimicrobial agent can reduce the bacterial load and support healing.

The concept that undisturbed wound healing, optimised by dressing choice, improves wound outcomes has become a focal point of consideration when evaluating wound management regimens in recent years. However, little evidence exists related to wound contact layers and the potential detrimental effects of the intimate contact with the wound bed. The aim of this study was to evaluate the effects of atraumatic wound contact dressings on the healing of partial-thickness wounds in comparison to untreated air-exposed wounds. Using an in vivo porcine wound model the handling properties of each dressing in terms of adhesion were analysed. Methods of wound characterisation included histological analysis of granulation tissue formation and epithelialisation and this was correlated with various clinical observations. Differences were found between dressings in terms of adherence to the wound bed and surrounding skin, capacity to retain wound exudates and enhancement of healing.

Over 90% of chronic wounds have biofilm infections, making the need for inhibiting reformation of biofilm post‐debridement paramount to support progression through the normal phases of wound healing. Herein, we describe a porcine wound model infected with methicillin‐resistant Staphylococcus aureus (MRSA) and examine the ability of an antimicrobial barrier composed of native type I collagen and polyhexamethylene biguanide (PCMP) to serve as a barrier to protect wounds and support progression through the innate wound healing cascade. Wounds were inoculated with MRSA and allowed to form a biofilm for 72 h, subjected to standard of care sharp debridement, then either left untreated or received PCMP for 5, 10, 15 or 20 days. Wounds were assessed for bioburden, wound closure and expression of genes related to wound healing. Wounds treated with PCMP exhibited statistically lower MRSA levels compared to untreated controls and achieved 90% closure by 2 weeks of treatment. Gene expression analysis demonstrated that by reducing bacterial load, wounds progressed through the innate wound healing cascade, while untreated wounds exhibited a dampening of the immune response. Additionally, for randomly assigned wounds, PCMP was not reapplied at dressing changes to assess the impact of inconsistent wound protection. At all timepoints, a resurgence in bioburden was observed following removal of PCMP if the wounds had not fully closed. This study highlights the value of PCMP as an antimicrobial barrier and the importance of protecting wounds through closure and resolution.

Introduction: Nitric oxide (NO) is a lipophilic gas with potent antimicrobial activity. Several in vitro and in vivo studies have demonstrated the broad-spectrum antimicrobial activity of NO-releasing compounds against bacteria, viruses, and parasites. The objective of this study was to assess the efficacy of topical NO formations with sustained release on microbial reduction in wounds. Materials and Methods: Swine was used as the preclinical animal model because of the similarities of porcine skin to human skin. Second-degree burn wounds were created in 3 pigs and then inoculated with Methicillin-resistant Staphylococcus aureus, Acinetobacter baumannii, or Candida albicans and covered with polyurethane film dressings to create biofilms. After 48 hours, wounds were then treated daily and then recovered for the bacterial burden assessments. Statistical analysis was performed using IBM SPSS statistics 27 using one-way ANOVA. Results: All treatments significantly reduced (P ≤ .05) the bacterial counts between assessment days 4 and 7. Wounds treated with the NVN4000 (1.8%) exhibited greater than 99.7% bacterial reduction on days 4 and 7. Significant differences (P ≤ .05) were observed in wounds treated with NVN4000 (1.8%) compared to silver sulfadiazine. Conclusions: These studies demonstrate that topical NO-releasing formulations effectively reduce the microbial burden of several microorganisms and exhibit superior antimicrobial efficacy compared to silver sulfadiazine in the porcine wound model.

Introduction: Wounds are colonized frequently by heterogeneous microflora. Pseudomonas aeruginosa (PA) and Staphylococcus aureus (SA) are two of the most isolated bacterial species from wounds, and both typically form highly organized biofilms. Nitric oxide (NO) is a short-lived, diatomic, lipophilic gas with antimicrobial activity. Recently, NO and its derivatives have been shown to exhibit broad-spectrum antimicrobial activity against bacteria, viruses, and parasites. Materials and Methods: P. aeruginosa strain ATCC 27312 or military isolate PA09-010 were combined with methicillin-resistant S. aureus strain MRSA USA300 to demonstrate the ability of NO to reduce polymicrobial infections in a porcine wound infection model. Deep partial-thickness wounds (10 mm × 7 mm × 0.5 mm) were made on four animals using a specialized electrokeratome. Wounds were inoculated with MRSA USA300 combined with PA09-010 in three animals and MRSA USA300 combined with PA27312 in one animal, then wounds were covered with polyurethane film dressings. After 48 hours, three wounds were recovered for baseline enumeration. The remaining wounds were randomly assigned to treatment groups and treated once daily. The NO topical gels tested were combinations of two phases, ointment phases with various concentrations (2–20%) combined with hydrogels with fast or slow release kinetics. A 4-day study with microbiological recovery was conducted on day 4. A separate 7-day study was also conducted, with microbial burden assessed on day 7. Results: The largest efficacy against MRSA USA300 was observed for the NO formulation with 2% concentration and fast release kinetics. This treatment reduced the MRSA USA300 bacterial count by more than 99.97% and 99.95% from baseline in wounds co-infected with PA09-010 and PA 27312, respectively, at day 7. Treatments showed a minimal efficacy against PA27312 and PA09-010 strains in both assessment times. MRSA USA300 was reduced to a lesser extent when it was combined with PA27312 as compared to PA09-010. Conclusions: These studies demonstrate that NO-releasing topical formulations effectively reduce the MRSA burden in established biofilms composed of multiple microorganisms. Minimal efficacy against PA was observed. It has been demonstrated that MRSA bioburden is significantly reduced when inoculated together with P. aeruginosa. A better understanding of mechanisms of host–bacteria interactions, in single or mixed species biofilms, may lead to the development of novel therapeutic approaches. Overall, NO offers a promising alternative treatment against MRSA in polymicrobial infections.