A team of scientists from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC, PAS; Warsaw, Poland) has developed a novel device, reportedly capable of testing antibiotic combinations in fewer than 12 hours and for thousands of samples at a time.
Described in Micromachines, the team claims that the device - designed to replace strip tests used at the point-of-care - is cost-efficient, fast and reliable, suggesting that the device may provide patients with a stronger chance of fighting disease and infection.
In developing the testing kit, the team aimed to combine simple methods to produce an easy bacterial susceptibility test requiring fewer reagents and antibiotics than traditional agar-based susceptibility tests. The novel testing kits is available as an ‘Etest’ and allows users to choose how to visualize data.
We wanted to test antimicrobial susceptibility as simply as possible, but not only for a single agent but also for combinations or under different conditions," explained Project Supervisor, Ladislav Derzsi (IPC PAS).
To deliver this new device, we matched several things that were discovered independently. For example we used standard UV and soft lithography techniques which are very common methods to fabricate microfluidic devices and we combined it with non-contact printing on a machine which was designed especially for us," Derzsi continued.
By adopting this combination of methodologies and employing the use of 3D printers, the team was able to position tiny droplets of antibiotic solutions of differing concentrations into microwells with very high precision.
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[The 3D printers] have small nozzles and using piezoelectric forces they deliver very precise amounts of liquid: nanoliters to picoliters or even femtoliters. We use similar technique only instead of ink we use antibiotics and we inject them not on paper but onto a soft elastomer. We let it slowly dry out under controlled conditions. The aqueous phase - water - evaporates and we're left with just the very small amount of antibiotic," Derzsi added.
One of the greatest advantages of the device, aside from ease-of-use, is the flexibility of the testing option available. Sterile plates can be produced on demand with different antibiotics in differing combinations.
We used plates with six single antibiotics in eight different concentrations and - to increase the precision - in eight repetitions each. We also tested pair-wise combinations of these six antibiotics in several repetitions. It is possible to test combinations of an arbitrary number of different antibiotics, inhibitors and adjuvants in one well," Drezsi further explained.
The team claims that this device could be a step towards personalized medicine, but may also be a useful tool in identifying novel combinations of antibiotics that may not have previously been considered.
Furthermore, the scientists believe that the device could be adapted in the future for the printing of primers for digital PCR to identify particular genes and antibodies.
Sources: Opalski AS, Ruszczak A, Promovych Y, Horka M, Derzsi L, Garstecki P. Combinatorial antimicrobial susceptibility testing enabled by non-contact printing. Micromachines. 11(2), 142 (2020); http://ichf.edu.pl/press/2020/04/IChF200421a_PL.pdf
Lead image: 'Finding the best therapy against bacterial infections is always challenging. Researchers from the Laboratory of Microfluidics and Complex Fluids, IPC PAS invented a microfluidic device which allows to test multiple antibiotics and antibiotic combinations at once.' Credit: Grzegorz Krzyzewski, IPC PAS