A rapid antibiotic susceptibility testing (AST) platform using multiplex static gradients - Summary: This project aims to prototype an innovative microfluidic reporting system that identifies effective antibiotics within 30 minutes for acute bacterial infections, such as sepsis. Bacteria cause widespread diseases, including urinary tract infections (UTI), acute lung infections, and bloodstream infections. Prescriptions to treat acute bacterial infections are often empiric, using broad-spectrum antibiotics at high doses, because the urgency of treatment does not allow for lab test results that take hours or days. However, this practice risks ineffective treatments, disruption of the healthy micro biome, and, more drastically, the development of antibiotic resistance, which can deprive future effective antibiotic treatments when needed. Timely microbial susceptibility to narrow-spectrum antibiotics at the clinic site is impractical because standard antibiotic susceptibility testing (AST) takes 2~3 days and requires well- equipped facilities and skilled laborers. Recently, researchers have developed alternative AST tests with great potential using microfluidic devices. These methods, however, mainly rely on bacterial growth, which takes hours, are incapable of testing more than a single bacterial species or a few antibiotic conditions, or require better accuracy and throughput. The field needs a rapid, inexpensive, and accurate AST platform to define individualized treatment plans. We propose to prototype a fast and precise AST platform to provide insights into effective treatments of acute bacterial infections. Our solution recognizes that motile bacteria, the primary source of common bacterial infections, swim away from effective antibiotic gradients and quickly lose their motility when exposed to survival doses of effective drugs. In Aim I, we will design and microfabricate a novel microfluidic device to generate multiplex static gradients of multiple antibiotics simultaneously. The multiplex gradient device is cheap to fabricate, easy to operate, and capable of simultaneously evaluating the effectiveness of multiple antibiotics based on bacterial chemotaxis and growth analyses when needed. In Aim II, we will map and quantify bacterial swimming behaviors under bright-field microscopy to report on antibiotic effectiveness in real time. In Aim III, we will optimize the rapid AST platform to screen effective antibiotics against known and unknown bacterial samples. By integrating robust microfluidic chemotaxis in multiplexed antibiotic gradients with advanced image processing, the rapid AST platform will provide timely insights for physicians to prescribe individually optimized treatments for acute bacterial infections, dramatically decreasing the waiting time from days for standard AST results to 30 minutes for motile cell-induced infections and 60 more minutes for non-motile cell-induced conditions. This prototype project will fulfill the primary objective of an AREA program by involving nine undergraduate students with various backgrounds in biomedical research and lay the foundation for follow-up grant submissions to screen clinical samples.
