(280i) Electrochemical Sensors for the Rapid Detection of Pseudomonas Aeruginosa in Polymicrobial Environments

A major cause of death among hospitalized patients results from infections acquired within the hospital setting. Over 1.4 million people experience infection complications each year, most notably from surgical wounds and pneumonia. Pseudomonas aeruginosa is a bacterial pathogen commonly found in these nosocomial infections. P. aeruginosa produces a small tricyclic molecule known as pyocyanin and because it is redox-active, it can be detected using electrochemistry. As a unique by-product of P. aeruginosa, pyocyanin is a useful biomarker for identification and detection of this opportunistic pathogen. It has been previously shown that electrochemical sensors can be used to detect P. aeruginosaâ??s production of pyocyanin in complex media environments. However, further research is needed to show how P. aeruginosa behaves when co-cultured in a complex environment with other bacterial pathogens. This study addresses this need by electrochemically monitoring P. aeruginosaâ??s production of pyocyanin in polymicrobial samples.

A total of 5 liquid cultures of different bacteria (Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Enterococcus faecalis) were grown overnight at 37 °C in lysogeny broth (LB) or trypticase soy broth (TSB) growth media. From these stock cultures, different polymicrobial combinations were tested, starting with single species inoculated with P. aeruginosa. From there, combinations of three bacterial pathogens were tested including a final sample that contained all five bacterial species. Production of pyocyanin was monitored every hour for the first 24 hours and then every 5 hours afterwards for a total of 3 days. Electrochemical detection was completed with 100 µL of liquid sample placed onto a disposable, screen-printed sensor. Measurements were recorded using square wave voltammetry at an amplitude of 0.05 V and a frequency of 15 Hz.

Measurements of current versus applied voltage were recorded for each of the different bacterial samples. Using a calibration curve of pyocyanin standards, the measured current can be correlated to the pyocyanin concentration in the sample. The study found that P. aeruginosa produces pyocyanin at similar rates, regardless if other bacterial pathogens are present. This data is useful towards developing a rapid point-of-care diagnostic sensor for P. aeruginosa in healthcare-associated infections that contain a number of different bacterial pathogens.