LabImageXpert: imaging platform for mechanism-resolved detection of antimicrobial activity via β-galactosidase assay

Antimicrobial resistance (AMR) has emerged as a global crisis, responsible for millions of deaths annually. Traditionally used antimicrobial susceptibility testing (AST) methods, such as disk diffusion and broth dilution, suffer from limitations including prolonged incubation time, inconsistent results, and high instrumentation cost. To address these challenges, we present in this study our novel, cost-effective antimicrobial detection assay equipped with a highly sensitive quantification system, LabImageXpert. Our antimicrobial detection system leverages the ability of β-galactosidase to convert colorless X-gal to an intense insoluble blue colored product. Unlike traditional MIC assays, LabImageXpert enables image-based, mechanism-specific growth assessment. During our investigation, we tested compounds already known to possess antimicrobial properties against our antimicrobial assay and found that it could not only detect the antimicrobial activity but also reveal the mechanism of action behind their antimicrobial activity, i.e., bacteriostatic and bacteriolytic. Further, this system contains a high-resolution DSLR camera to image samples in a microtiter plate placed inside a special box. The captured images are processed using the open-source software. We performed an experiment exclusively to test its ability to quantify minute variations in bacterial growth over time. The results showed that it could detect minute deviations in average pixel intensity over time. LabImageXpert detected bacteriolytic activity of compounds within 3 h. Our findings suggest that the LabImageXpert provides a reproducible, scalable, and cost-effective alternative platform for antimicrobial research in teaching, research and clinical diagnostic labs.