Rapidly Detected Common Wound Pathogens via Easy-to-Use Electrochemical Sensors

Abstract

The detection of infection in clinical practice is time consuming and laborious. The ability to monitor infection status in real time, for example in wounds, would enable earlier intervention and improved prognosis. This study describes the real time electrochemical detection of clinically important wound pathogens. Using impedance spectroscopy in conjunction with a normalisation approach, the growth of Proteus mirabilis in LB medium was detected 1 hour after sample inoculation at a cell concentration of 7.4 x106 CFU/mL. Furthermore, a significant decrease in charge transfer resistance arose over the 24 hour growth period (p = 0.009), modelled using a simple equivalent circuit. Additional experiments performed in 0.9% w/v NaCl (where growth was inhibited) indicated that processes facilitated by this organism’s metabolism and growth dominated the impedance response in LB medium. Further, immediate detection of a high concentration of P. mirabilis cells was possible (5.0 x108 CFU/mL). Finally, a simulated wound fluid was used to explore the growths of P. mirabilis, Pseudomonas aeruginosa and Staphylococcus aureus in a more complex environment representative of a wound bed. Similar changes to normalised impedance were observed, and decreases in normalised phase emerged as a characteristic indicator of bacterial growth. The ability of these low cost sensors to rapidly detect bacteria highlights their potential for adoption into point-of-care infection monitoring devices.