Improved resolution for antibiotic susceptibility in QuickMIC®

Sammanfattning

Background: The crisis of antibiotics resistance demand faster, more accurate diagnostics tools for antibiotic susceptibility testing (AST). I studied the effect of an alternative analysis chamber construction in a novel rapid AST system named QuickMIC®, to improve the detection resolution and range. The test chamber is localized in a part of the test cassette called the “slider” and is the part where the test for minimum inhibition concentration (MIC) is located. The test resolution is dependent on optical quality, and with the current production method there are horizontally stretched bacterial colonies in some of the regions. The goal of this project was to see if it was possible to decrease the frequency of these optically bad regions by improving the slider production method. Method: An improved production method was examined, using post-laser polishing to finalize slider dimensions. The alternative slider was cut from thicker material compared to the current slider and had the sides polished to reduce the diameter, to avoid the formation of a cylindrical lens shaped inlet and outlet of the microfluidics chamber. The performance of the sliders was compared by looking at the frequency of horizontally stretched colonies. Results: The bacterial colonies of regions near the inlets, outlets and the middle of the test chamber were studied in both the current- and alternatives slider. The result show that colonies in the middle were highly similar in both sliders, showing a large variety in stretch direction and low accuracy. Similar results could be observed in the edge-located colonies of the alternative slider. The edge-located colonies of the current slider are the only one observed to greatly differ from the rest, showing horizontal stretch colonies and high accuracy. Conclusion: The conclusion from this is that the colonies at the edges of the alternative slider is more like the middle colonies then the edge colonies in the current slider. This shows that the frequency of horizontally stretched colonies decrease in the alternative slider.