A microfluidic device for antimicrobial susceptibility testing of combined antibiotics by using broth dilution method

Abstract

A simple microfluidic device which can perform antimicrobial susceptibility testing (AST) of combined antibiotics against antibiotics-resistant bacteria has been presented. A new approach to determine the fractional inhibitory concentration (FIC) index of two antibiotics by performing broth dilutions automatically was proposed and its performance was highly consistent with manual operation. The experimental results showed that the developed device could achieve on-chip dispensation/dilution/mixing accurately and interpret AST results visually. A test using two common antibiotics (vancomycin and ceftazidime) was performed on one clinical isolate of vancomycin-intermediate Staphylococcus aureus (VISA) based on the FIC indices. It is the first time that a microfluidic device was demonstrated to be capable of determining the FIC index of combined antibiotics against bacteria by performing AST automatically. With its high flexibility and reliability, the proposed device provides a simple method to explore drug cocktails for combined antibiotic therapy.