Detection of chronic wound infection using impedance spectroscopy

  • Sara Louise Kendrick

Student thesis: Master's Thesis

Abstract

Chronic wounds are a rapidly growing burden to patients and healthcare systems globally. The rising incidence of both obesity and diabetes worldwide, coupled with an aging population, are contributors to predictions that a greater number of patients will exhibit chronic wounds in the future. It has been shown that bacteria in wounds form persistent biofilms. Successful wound management calls for rapid, accurate diagnosis to control infections, as well as minimizing disruption to the wound site. Historically, clinical identification of infection at a wound site has relied on swabbing and culturing methods, and in recent years progress has been made in using electrochemical biosensors for the rapid detection of microorganisms. This study explores the detection of infections using impedance spectroscopy to monitor bacteria.Initial electrochemical impedance spectroscopy experiments using label-less carbon screen printed electrodes were conducted to characterise the impedance signatures of Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus faecalis. These bacteria, which are commonly found in chronic wound infections, were cultured in both rich laboratory media and simulated wound fluid. In the final part of the study a wound bed model was produced that simulated the environment representative of a wound infection including two dressing types, one honey-based and one silicone. Experiments were performed to assess the effectiveness of the impedance detection technique for chronic wound infections using this model.Differences in impedance characteristics were seen across bacterial strains in laboratory media and simulated wound fluid. The greatest changes were seen in P. aeruginosa, with smaller impedance signatures identified for S. aurues. Signatures were also observed for E. faecalis with significant differences seen in some regions of the impedance spectrum.Additionally, it was found that a honey-based dressing resulted in lower cell density of P. aeruginosa colonies after 72 hours and that prominent features in the phase component of impedance were present. Findings from this study support the possibility that impedance spectroscopy could be used for the identification of chronic wound bacteria in a future point of care device.
Date of Award1 Oct 2016
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SupervisorPatricia Connolly (Supervisor) & Andrew Ward (Supervisor)

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