Background:
Timely administration of appropriate antibiotics is paramount for effective sepsis management. Conventional diagnostics are time-consuming, requiring up to 48-hours, with increasing antimicrobial resistance exacerbating the risk of treatment failure. We aimed to develop a rapid antimicrobial resistance diagnostic for earlier therapeutic guidance, aiding clinicians in prescribing.

Methods:
The CyteCount device was developed to study bioelectricity at a single-cell level. We used it to assess the effect of different antibiotic exposure times on viability and vitality of resistant and susceptible strains in both Gram-positive and Gram-negative bacteria. A comparison with traditional plate counting methods validated the accuracy and speed of our approach.

Results & Discussion:
CyteCount analyses detected resistance and susceptibility in <3hours for Gram-positive and Gram-negative strains. It identified more viable cells comparatively after treatment with a certain class of antibiotics, displaying a unique membrane potential response profile. Single-cell electrophysiological analyses offered additional insights.

Conclusion
CyteCount viability counts distinguished resistant from susceptible strains. Additional analysis enabled earlier detection of cells’ response to antibiotic stress, potentially detecting resistance in under two hours. CyteCount shows promise for early selection of appropriate antimicrobial therapy. Further work should assess its single-cell data analyses against solid-phase cytometry and study electrophysiological responses in slow-growing microorganisms.