(170f) Selective Pseudomonas Aeruginosa Detection with Embedded Electrochemical Sensors

With the rise in antibiotic resistant bacteria there is a need to efficiently identify the bacteria causing infections to ensure the appropriate administration of antibiotics. Resistant Pseudomonas aeruginosa is of particular concern for people with compromised immune systems suffering from lung infections and is included on the Center of Diseases Control's (CDC) list of dangerous antibiotic resistant pathogens. Current approaches to P. aeruginosa’s detection involve lengthy incubation periods on culture plates (24+ hours) or detection of the bacteria’s DNA in a patient’s sample using polymerase chain reaction (PCR) requiring trained technicians to effectively prepare and analyze the samples. P. aeruginosa's clearance from the lungs is inhibited by the production of pyocyanin, a redox molecule unique to this bacterium associated with neutrophil death, making the electrochemical detection of P. aeruginosa via pyocyanin an exciting option. This paper proposes the electrochemical detection of pyocyanin produced by P. aeruginosa as it diffuses through selective growth agar to indicate P. aeruginosa’s presence.

Disposable embedded electrochemical sensors were made by inserting screen-printed three electrode cells into Petri dishes then surrounding with sterilized King’s A media. King’s A media was chosen for its ability to up regulate pyocyanin production. P. aeruginosa strain PA14 at an infectious dose (≈10⁶ cells) was placed onto the agar above the working electrode. Samples and devices were incubated at 23, 37, or 42 ºC and interrogated with square wave voltammetry every hour. The maximum current in the potential window of -0.5 to 0 V was recorded versus time and the plates were visually observed to monitor the growth of the culture on the plate. The current response of the embedded electrodes was found to increase over time due to the production of pyocyanin. Importantly the electrical signal increase occurred at a much earlier time compared to the formation of bacterial cultures indicating an important reduction in the time to detection for PA14. Furthermore this method combines the ease of use of agar plates with a decreased detection time that requires no complicated sample preparation steps (compared to PCR). The reported results highlight the fast, selective detection of P. aeruginosa with future applications for detection in patients suffering from lung infections.