Mechanical engineers from the Korea Advanced Institute of Science and
Technology have developed a microchip antibiotic testing platform that takes
only six to seven hours to determine the appropriate medication.

“Trying to figure what drug to use at what dosage, in the fastest time possible,
is key in successfully treating bacterial infections,” said Jessie Jeon, an
author on the paper.

Clinicians often treat life-threatening infections with a cocktail of
antibiotics, hoping that one of the antibiotics will stop the bacterial infection.
However, blanket-prescribing antibiotics contributes to the rise in bacterial

“Figuring out the effect of different combinations of drugs in a simple manner
is likely to have a big impact on health,” said Jeon. She explained that her
team’s speedy microfluidic system was the first for which combinatorial
treatments had been tested.

The speed and success of the Korean team’s new antibiotic susceptibility
testing system is due to two key innovative design features.

The first feature was developing an antibiotic dosage range, crucial for
calculating the minimum inhibitory dosage that prevents bacterial growth. By
continually pumping antibiotics through the half-millimeter-wide channels in
the microchip, the team establishes a dosage range through microchip within 30
minutes. A critical time saver, the dosage range enabled the team to determine
the minimum inhibitory dosage within a single test.

The second feature was using a convenient method to quantify bacterial growth
within the microchip. Images were taken of the agar-encased bacteria and the
difference in color between areas of agar at a higher antibiotic concentration,
where no bacteria grew (which were dark), and the more reflective white
regions, where bacterial colonies grew more easily, was quantified on a
position-specific grayscale.

Alignment of the five antibiotics tested in this new system with the clinical
gold standard measurements suggests that the microchip system is sensitive
enough for clinical application, Jeon added.

“We can see that our assembly works pretty robustly with a single drug, and
have also shown it can work with two drugs; now we want to further optimise the
application to combinatorial drugs,” said Jeon.


 Reference:  Seunggyu
Kim, et al. Microfluidic-based observation of local bacterial density under
antimicrobial concentration gradient for rapid antibiotic susceptibility
testing. Biomicrofluidics 13,
014108 (2019). Published 5 February 2019.