Colorimetric Ready-to-Use Microfluidic Chips for Rapid Antibiotic Susceptibility Testing of Methicillin-Resistant...

Many phenotypic resistance tests have been developed for Methicillin-resistant Staphylococcus aureus (MRSA), but they still have disadvantages such as long incubation times, complicated procedure and a lack of portability. Herein, we designed ready-to-use microfluidic chips to use more advanced and new methods for analyzing antibiotic resistance specifically for the rapid detection of MRSA. Anthocyanin molecules, which change color depending on the pH value of the reaction medium in the microfluidic chip wells, are utilized as pH indicator in the test. The color change in the wells depends on the inhibition of antibiotic-resistant or susceptible bacteria at varying cefoxitin doses. The antibiotic resistance profiles of MRSA to multiple doses were revealed on a single chip. The obtained colorimetric responses were analyzed using a mobile application and color image processing techniques. The feasibility of the system was demonstrated using standard reference strains (S. aureus ATCC 43300 and ATCC 25923). Thus, this proof-of-concept study shows that antibiotic resistance detection can be performed in a few hours with minimal device requirements, warranting further validation with clinical isolates.