Fast antibiotic susceptibility test-integrated microfluidic chips for detection of carbapenem/colistin-resistant bacteria using smartphone-based analysis.

Although many phenotypic methods have been developed for the detection of antibiotic-resistant bacteria, this emerging field still requires more rapid, practical, and economic approaches. Herein, we report a colorimetric phenotypic antimicrobial susceptibility test integrated into a microfluidic chip (mc-AST) for the detection of carbapenem (Car)- and colistin (Col)-resistant bacteria. A key component of the mc-AST is anthocyanin, a natural pH indicator that changes color based on the pH of the reaction environment. The mc-AST contains corresponding antibiotics to suppress the growth of susceptible bacteria. The color changes in the mc-AST can be detected by the naked eye and through image processing using a smartphone. The novelty of this study lies in the first ever integration of an anthocyanin-based antibiotic susceptibility test into a microfluidic chip. This integration provides a resistance profile for multiple doses of antibiotics on a single chip. Ultimately, the mc-AST reduces the workload and delivers results within 2 hours.