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Aim: The presence of bacteria in a wound can prevent wound healing and lead to chronic infections. Commercial wound dressings may aim to physically remove bacterial load from a wound through attachment to a dressing surface. Bound bacteria are then removed during the dressing change. With repeated applications, the bacterial load of the wound can be reduced to allow the immune system to fight the infection. In this study we analyzed key genes involved in the bacterial attachment process alongside bacterial quantification, to further understand the wound dressing mode of action. Method: A Pseudomonas aeruginosa inoculum was prepared and 100 µL were applied to the surface of a commercial wound dressing, standard gauze, and a positive control. Each sample was incubated for 24 hours at 37oC under static conditions. Following incubation, 1 mL of planktonic bacteria were taken from each sample and the remaining bacteria were removed from the sample by washing in sterile PBS. Adhered bacteria were recovered in PBS and both DNA and mRNA were extracted for analysis using qPCR or RT-qPCR: Results / Discussion: Viable-only quantification of P.aeruginosa: No significant difference was detected in bacterial quantification between adhered samples and planktonic samples following 24 hours incubation (p > 0.05). Transcription profiles of the pelA and rsaL genes: Statistical difference was detected in the pelA and rsaL genes between the commercial wound dressing and the gauze following 24 hours incubation (p < 0.05). Conclusion: These results demonstrated that despite a similar bacterial load, transcription data differentiated between test items making this a novel but simple method for detection and quantification of bacterial adherence to a wound dressing. [ABSTRACT FROM AUTHOR]

Aim: The CDC Biofilm Reactor® is widely used for commercial product testing of biofilm established onto solid state coupons. Bacterial quantification through standard microbiological techniques is mainly used in the assessment of biofilm removal or prevention. However, it widely known that bacteria alter gene expression profiles as environmental pressures evolve. A greater understanding of key genes in response to the presence of antimicrobial products will allow wound companies to understand further about the mode of action of their products in relation to biofilm prevention and biofilm removal. Method: A Pseudomonas aeruginosa inoculum was prepared and transferred to a CDC Biofilm Reactor® containing stainless steel coupons. The reactor was incubated for 72 hours at 37oC under shaking conditions. Both biofilm bacteria attached to the coupons and planktonic bacteria were recovered at six time points between 2 hours and 72 hours as the biofilm developed, and gene expression was monitored from both coupons. Results / Discussion: All investigated genes were significantly upregulated by 18 hours, with four (pelA, rsaL, pcrV and gyrA) peaking at 18 hours, and the remaining four (pslA, psqC, acpP and cbrA) peaking at 24 hours. Conclusion: Results showed that the peak expression for all eight genes under typical P. aeruginosa biofilm formation occurred between 18-48 hours post inoculation, which coincides with biofilm development. In addition, despite a similar bacterial load, most genes had over 100 times fold change in biofilm samples compared to planktonic, providing the framework for analysing mode of action for wound care products targeting biofilms. This novel method would be recommended for screening antibiofilm products for their ability to prevent and disrupt biofilms. [ABSTRACT FROM AUTHOR]

Aim: To track wound healing in response to a wound care solution1 using a full thickness wounded skin tissue model. Method: Wounded full thickness tissue models containing viable cells were treated with either a wound care solution1 or DPBS every 48 hours for 7 days. On days 1, 2, 5 and 7 models were processed for immunostaining, fluorescent confocal microscopy and measurement of wound closure. Pro-inflammatory markers (IL-1β, TNFα, IL-6) were quantified using an ELISA. ANOVA was used to determine statistical differences. Results / Discussion: Following 2 days treatment, the average wound diameter of models treated with a wound care solution1 was significantly reduced compared to controls, indicating an increased wound closure response. At Days 5 and 7, models treated with a wound care solution1 showed complete coverage of the wounded area with fresh keratinocytes leaving no exposed dermal fibroblasts visible. Tissue models treated with a wound care solution1 produced comparable levels of IL-1β, TNF-α and IL-6 to models treated with DPBS. Successful and timely wound healing requires a balance of both fibroblast and keratinocyte growth. A lack or imbalance of either cell type can lead to increased inflammatory responses and prolonged wound healing2. The wound model used mimics this scenario closely by removing the top keratinocyte skin layer of a full thickness in vitro human skin model, exposing the dermal fibroblast layer underneath and can therefore provide an indication of performance in patients. Conclusion: In conclusion, the wound care solution1 showed more rapid wound closure compared to the DPBS control and proinflammatory effects were not significantly different. [ABSTRACT FROM AUTHOR]