Detection of bacterial metabolites for the discrimination of bacteria utilizing gold nanoparticle chemiresistor sensors

•Gold nanoparticle chemiresistors were investigated for healthcare diagnostics.•Chemiresistors indirectly detected bacteria by sensing bacterial metabolites in complex liquid samples.•Early work indicates a limit of detection below 3.7×106CFU/mL within 6h from low inoculation concentrations.•An array of chemiresistors clearly discriminated four different bacterial species. The current methods for detecting and diagnosing bacterial infections have limitations that put lives at risk and threaten to burden healthcare systems with antibiotic resistant strains. Within the field of diagnostics, efforts continue to focus on developing new tools that are fast, easy to use and accessible to resource poor settings. Chemiresistor sensors are amongst new technologies being investigated to meet present needs for diagnosing diseases. Potential advantages of the technology include its amenability to point of care diagnostics, inexpensive components and rapid response times. Here, we present work on utilizing gold nanoparticle chemiresistors for the rapid detection and discrimination of bacteria in liquid samples. The detection principle is based on the distinct metabolic differences associated with species specific bacterial growth. For our proof of concept phase, the supernatant of defined bacterial liquid broth cultures were used. Principal component analysis on data from an array of gold nanoparticle chemiresistors was able to discriminate the culture supernatants of four bacterial species (Escherichia coli, Bacillus subtilis, Staphylococcus epidermidis and Enterobacter aerogenes). With basic unoptimized sensors, the detection limit for E. coli was indicated to be below 3.7×106CFU/mL and detection was achieved within 6h from low inoculation levels (102CFU/mL). Results indicated for the first time that gold nanoparticle chemiresistors can successfully detect and discriminate bacteria indirectly from liquid samples. The outcome of this investigation is positive for the continued development of gold nanoparticle chemiresistors for a much needed point of care diagnostic tool for rapidly detecting bacteria.