Detection of Antimicrobial-Induced Survival/Dead Bacteria via mEos4b Photoconversion: A Preliminary Study.

The escalating prevalence of hospital-acquired infections poses a critical challenge for healthcare systems worldwide. Effective management requires rapid identification of pathogens and their antibiotic resistance profiles. In this study, we utilized the photoconvertible mEos4b protein, which transitions from green to red fluorescence upon blue light exposure, to distinguish live from dead bacteria. The mEos4b gene was cloned into a prokaryotic vector and expressed in Escherichia coli BL21. The Minimum Inhibitory Concentration (MIC) of the transgenic bacteria was determined for five antibiotics, followed by a post-antibiotic effect assessment over a two-hour exposure period. The optimal photoconversion time for mEos4b was established as 90 seconds, and confocal microscopy was used to visualize live (green) and dead (red) cells post-exposure. The mEos4b-TR system proved highly specific, accurately distinguishing live and dead bacteria without producing false positives, even in control groups, which is a common issue in commercial live-dead kits. By relying on cellular metabolic activity rather than dyes, this system minimizes nonspecific interactions and contamination, making it more reliable than traditional methods prone to false readings. These results highlight the potential of the mEos4b-TR system as a superior alternative for rapid, precise bacterial viability assessments, particularly in determining antibiotic susceptibility. This preliminary study demonstrates the system's differentiation of viable and non-viable cells, suggesting its potential application in future studies involving novel antibacterial agents to refine antibiotic sensitivity testing.