Freeze-Dried Bacterial Cellulose-Based Point-of-Care Device for Antibiotic Susceptibility Testing (AST).

Antimicrobial resistance is a major global health challenge, and the current gold standards for antibiotic susceptibility testing typically require 16-48 h. This study reports bacterial cellulose-based devices for rapid colorimetric antimicrobial susceptibility profiling using two laboratory strains, E. coli DH5-α and Staphylococcus aureus. The freeze-dried bacterial cellulose substrate, with its nanofibrous structure and high porosity, is evaluated for its ability to accommodate bacterial inoculum, antibiotic, and a halochromic dye. Structural analyses show improved moisture retention compared to filter paper, which tends to dry rapidly. Using this platform, susceptibility to ampicillin and resistance to nalidixic acid become visually distinguishable within a single doubling time. An unsupervised K-means clustering algorithm is employed to segment colorimetric outputs and quantify viability-driven changes in the assay. This study presents freeze-dried bacterial cellulose devices that provide a clear visual distinction between susceptibility and resistance within a single bacterial doubling time.