Charlotte R Morgan PhDc - Posters

Title:

Flash Talk: Dissecting the impact of synthetic wound fluid on antimicrobial susceptibility and biofilm formation

Authors:

• Charlotte R. Morgan
• Aleyna Yarranton
• Lydia C. Powell

Abstract:

Background

Chronic wounds are characterised by persistent microbial colonisation, biofilm formation, and prolonged inflammation, creating a complex host-pathogen environment that impairs tissue repair, resist conventional treatment and harbour multi-drug-resistant bacteria. The biochemical composition of the wound milieu plays a key role in microbial behaviour and may influence interactions with host defence mechanisms. However, many in vitro infection models fail to reflect these conditions, limiting their relevance to chronic wound pathogenesis. This study investigates the use of synthetic wound fluid (SWF) as a physiologically relevant system to explore microbial adaptation within wound-like environments.

Methods & Results

Chronic wound bacterial isolates, Pseudomonas aeruginosa PAO1 and Methicillin-resistant Staphylococcus aureus (MRSA) 1004a were cultured in multiple formulations of SWF, comprised of either fetal bovine serum (FBS), human-derived serum or bovine serum albumin (BSA) compared to standard laboratory media Mueller Hinton Broth (MHB). Microbial growth and antimicrobial susceptibility was assessed using minimum inhibitory concentrations (MIC) assays. Biofilm architecture was analysed via confocal laser scanning microscopy with COMSTAT quantification, while Atomic force microscopy (AFM) and electrophoretic light scattering (ELS) were used to assess cellular mechanical properties and surface charge. P. aeruginosa and MRSA growth was supported in FBS. Notably, MRSA had increased antimicrobial susceptibility when grown in both FBS and human serum to the antibiotic of last resort, colistin, compared to MHB, resulting in a reduced MIC value (16 µg/ml vs 256 µg/ml). Biofilm structure and stability differed between conditions, when grown in FBS in comparison to MHB (p < 0.05). AFM and ELS assays also revealed alteration of the mechanical properties and bacterial surface charge when grown in FBS, in comparison to MHB (p < 0.05).

Conclusion

Overall, SWF modulates microbial behaviour, altering growth, responses to therapeutics and biofilms. Using a physiologically relevant model improves understanding of chronic wound infection processes and helps guide the development of targeted therapies.