Validation of biofilm formation on human skin wound models and demonstration of clinically translatable bacteria-specific volatile signatures

Abstract

Biofilms are major contributors to delayed wound healing and there is a need for clinically relevant experimental models to assess theranostics. Microorganisms release volatile organic compounds (VOCs) and the ability to identify these in infected cutaneous wounds could lead to efficient non-invasive diagnosis. The aims here were to develop and assess bacterial biofilm formation and identify their VOC profiles in an in vitro model and validate in human ex vivo incisional and excisional cutaneous wound models. Biofilm development was assessed using multiple microscopy techniques with biofilm-forming deficient controls and quantified using metabolic and biomass assays; and VOC production measured by gas chromatography-mass spectrometry. The production of most VOCs was affected by biofilm development and model used. Some VOCs were specific either for planktonic or biofilm growth. The relative abundance of some VOCs was significantly increased or decreased by biofilm growth phase (P < 0.05). Some Staphylococcus aureus and Pseudomonas aeruginosa VOCs correlated with biofilm metabolic activity and biomass (R ≤ −0.5; ≥0.5). We present for the first time bacterial biofilm formation in human ex vivo cutaneous wound models and their specific VOC profiles. These models provide a vehicle for human skin-relevant biofilm studies and VOC detection has potential clinical translatability in efficient non-invasive diagnosis of wound infection.

Endogenous and microbial volatile organic compounds in cutaneous health and disease

“…One alkene (1-undecene) was present in both PA and SP biofilms in all wound models at all time points, while several other VOCs were uniquely identified in SP and PA biofilms respectively ( Table 1). There were 2 VOCs (2-methyl-1-propanol and 3-methyl-1-butanol) common to all 3 bacteria, but differences in their relative abundance permitted differentiation between bacterial species [102]. These early results highlight the potential utility of VOCs in assessing biofilm development.…”

Volatilomes of Bacterial Infections in Humans

“…Wounds are a major burden on healthcare systems because their treatment is often complicated with chronic infections and potentially the development of biofilms, which makes their eradication arduous. The volatilomes of S. aureus and P. aeruginosa biofilms have been recently studied for their potential in monitoring biofilm development and response to various treatments (Ashrafi et al, 2018(Ashrafi et al, , 2019.…”

Bioengineered Platforms for Chronic Wound Infection Studies: How Can We Make Them More Human-Relevant?

“…Recently, a human ex vivo cutaneous wound model for bacterial biofilms was developed to study the profile of volatile organic compounds (VOCs) produced by the metabolic activity of biofilm bacteria (Ashrafi et al, 2018). Using a comparison between in vitro biofilm growth on a polyester substrate and human ex vivo wound biofilms, identification and relative abundances of distinct VOC profiles were obtained for S. aureus, P. aeruginosa and S. pyogenes.…”