Portable Dynamic Laser Speckle Imaging for Rapid Antimicrobial Susceptibility Testing

Antimicrobial resistance remains a pressing global health threat. Conventional antimicrobial susceptibility testing (AST) methods are limited by long incubation times and centralized laboratory requirements, hindering timely decision-making in resource-limited settings. This study introduces a 3D printed, portable dynamic laser speckle imaging (pDLSI) device for rapid AST. This device has a 10 × 3 × 3 cm³ footprint, equipped with a low-cost laser diode, a lens assembly, and a cuvette sample holder. Speckle fluctuations induced by bacterial activity are captured on a cellphone camera, visualized using spatiotemporal decorrelation maps, and analyzed using machine learning to determine minimum inhibitory concentrations within 2-3 h. To demonstrate the performance, we studied two representative Gram-positive and Gram-negative bacterial strains (<i>Enterococcus faecalis</i> and <i>Escherichia coli</i>), along with two antibiotics (ampicillin and gentamicin). The simple construction, portability, and intuitive operation of the pDLSI system can potentially facilitate initial diagnostic decisions at the point of care.