A better assessment of the susceptibility of bacteria to antibiotics could change the way drugs are prescribed

WASHINGTON, D.C., Feb. 5, 2019 – We use antibiotics to treat bacterial infections, but the increase in antibiotic-resistant bacteria is forcing doctors and patients to cope with changing treatment plans. In addition, current laboratory tests to determine which bacterium is causing a particular infection take days and, in cases of severe infection, the results are often too late for the patient .

Mechanical engineers at the Korea Institute of Science and Technology recently developed a microchip antibiotic screening platform that only takes six to seven hours to determine the right drug.

"Trying to determine which drug to use, at what dose, as quickly as possible, is critical to successfully treating bacterial infections," said Jessie Jeon, author of the journal.

Clinicians often treat life-threatening infections with a badtail of antibiotics, hoping that one of the antibiotics will stop the bacterial infection. However, the antibiotics prescribed in general contribute to the increase of the bacterial resistance.

"Understanding the effect of different drug combinations in a simple way will likely have a significant impact on health," said Jeon. She explained that her team's fast microfluidic system was the first one for which combinatorial treatments had been tested.

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

The first feature was to develop an antibiotic dosage range, crucial for calculating the minimal inhibitory dosage inhibiting bacterial growth. By continuously pumping antibiotics into the half-millimeter channels of the microchip, the team establishes a dose range in a microchip within 30 minutes. The dose range allowed the team to determine the minimum inhibitory dosage in a single test, saving valuable time.

The second feature was to use a practical method to quantify bacterial growth within the microchip. Images were taken of the agar-coated bacterium and the color difference between the agar zones at a higher concentration of antibiotics, where no bacteria developed (which were dark) , and the more reflective white regions, where bacterial colonies grew more easily, were quantified on a position-specific gray scale.

The alignment of the five antibiotics tested in this new system on clinical reference measures indicates that the microarray system is sensitive enough for a clinical application, added Jeon.

"We can see that our badembly works quite robustly with a single drug and we have also shown that it can work with two drugs.We now wish to further optimize the application to combinatorial drugs," Jeon said. .

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The article, "Microfluidic Observations of Local Bacterial Density Under Antimicrobial Concentration Gradient for a Rapid Antibiotic Sensitivity Test," is written by Seunggyu Kim, Seokhun Lee, Kim Ju-Kang, Hyun Jung Chung, and Jessie S. Jeon. The article appeared in Biomicrofluidique on February 5, 2019 (DOI: 10.1063 / 1.5066558) and is accessible at the following address: http: // aip.scitation.org /do I/full/ten.1063 /1.5066558.

ABOUT THE NEWSPAPER

Biomicrofluidique publishes research highlighting the fundamental physico-chemical mechanisms badociated with microfluidic and nanofluidic phenomena as well as new microfluidic and nanofluidic techniques for diagnostic, medical, biological, pharmaceutical, environmental and chemical applications. See http: // bmf.aip.org.