Electrical Biosensor for Rapid Point-of-Care Diagnosis of Urinary Tract Infections and Antibiotic Susceptibility Testing

Avails Medical, Inc., Palo Alto CA

Investigators

Abstract

Project Summary Every year, over 8 million people are diagnosed with urinary tract infections (UTI's) in the United States alone. UTI's encompass bacterial infiltrations of the urinary tract and the most common bacterial infections worldwide. Together with the increasing threat of antimicrobial resistance and the lengthy diagnosis time, physicians are in need of technology that allows for rapid bacterial identification and their susceptibility to antibiotics at the point- of-care. Today's gold standard for point-of-care UTI diagnosis is dipstick testing, a calorimetric test strip that changes colors if bacterial and leukocyte metabolites are present in a urine sample. However, the sensitivity and specificity of dipsticks for those UTI markers are poor. For accurate diagnosis and antibiotic susceptibility testing, urine samples are sent for laboratory bacterial cultures, a process that takes up to three days. To bring rapid and accurate UTI diagnosis and antibiotic susceptibility testing to the point-of-care, we are developing a device that uses a silicon nanowire field effect transistor (SiNW-ISFET) to detect protons produced upon bacterial metabolism. In the device, bacteria from clinical urine samples are captured and concentrated on a filter that is in liquid contact with the sensor. Exposing the captured bacteria to a carbon source containing media with low buffering capacity and incubating at 37°C, we are able to 1) detect bacterial infections (?105 CFU/ml) by a significant pH change of the media and in as low as 10 minutes, 2) discriminate Gram-types by selective dye based inhibition of proton production by Gram-positive bacteria, and 3) detect antibiotic susceptibility and resistance when bacteria were exposed to the drugs. The three specific aims of this proposal address the optimization of the three assays and their validation in de-identified clinical urine samples. We will determine the accuracy of our technology by comparing our results with the laboratory gold standards including urine dipstick, disk diffusion, broth dilution and microscopic gram staining.