Investigating resistance and microbiota changes in response to commonly used wound dressings

One of the most recent studies on the cost burden of wound care in the UK, estimated 3.8 million patients with a wound were managed by the NHS in 2017/2018, with a cost of £8.3 billion (Guest et al., 2020). The use of silver based wound dressings has been reported to be associated with an average of £65.27 higher cost than a non-antimicrobial dressing (Urwin et al., 2022).

The use of silver as a disinfectant date back to ancient times (Klasen, 2000), however the research behind the antibacterial activity of silver has only increased noticeably over the last century, especially since the advent of silver nanoparticles and their use in wound dressings (Sondi & Salopek-Sondi, 2004; Lansdown & Williams, 2007). It is through this research that we now recognise that commonly isolated bacteria from wounds can indeed become resistant to silver (Randall et al., 2015; Wang et al., 2022).

Silver resistance in bacteria can occur endogenously through mutations, or exogenously through the acquisition of plasmids from other bacteria (Randall et al., 2015). Silver resistance can be associated with antibiotic resistance, for example silver resistance genes are known to be present alongside genes encoding Extended Spectrum Beta Lactamases (ESBLs) (Siddiqui et al., 2019, Sutterlin et al., 2014).

Previous studies have attempted to look at the effect of silver dressings on bacteria, however these have been based on in-vitro studies using either biofilm models (Doherty et al., 2023), simulated wound fluid (Norton & Finley, 2021; Said et al., 2014), or using in-vivo animal models (Burd et al., 2007).

The results of an internal wound swab audit for the year 2023, revealed that the microbiology service of Wales received just under 91,000 wound swab samples for the year, with approximately 44,500 coming from outpatient settings. The Swansea Bay area received just under 20,500 in total with approximately 9060 wound swabs coming from outpatient settings. Of the 20,500 swabs received members of the Enterobacterales group appeared on the report approximately 6,100 times.

This study will assess the effect of silver dressings on the wound bed microbiota, providing a more representative analysis of the complex interaction between the microbiota and wound environment. Furthermore, a clearer picture of silver resistance, ESBL, metallo-β-lactamases (MBL), AmpC and OXA gene carriage will be obtained.

I will use transcription metagenomics, with the aim of determining: the identity of all the organisms within the wound environment; any changes that may occur to the population; and the expression (‘switching on’) or suppression (‘switching off’) of any resistance genes following exposure to silver dressings.

We believe this will be the first time transcription metagenomics has been employed to analyse the microbiota of a wound bed, in response to wound dressings, within its natural environment.

Outputs

No outputs as yet, this is in the planning / waiting for IRAS phase.