Rapid Antimicrobial Susceptibility Test Cartridge for Resource-Limited Settings

DESCRIPTION (provided by applicant): Program Director/Principal Investigator (Last, First, Middle): Gau, Vincent Project summary and abstract Standard culture-based diagnosis of bacterial infections, including pathogen identification (ID) and antimicrobial susceptibility testing (AST), require 2-3 days for clinical sample acquisition to result reporting. The absence of definitive microbiological diagnosis at the point of care has largely driven the over- and misuse of antibiotics. While microbiological diagnosis has improved with the availability of high throughput, automated instruments in the larger clinical microbiology laboratories, the process remains time-consuming and requires significant technical expertise. Standard automation instruments are bulky and typically require a priori isolation of the pathogens from the body fluid samples prior to AST . The significant work burden of a modern clinical microbiology laboratory has led increasingly to the practice of outsourcing of clinical laboratory tests. Development of a point-of-care platform capable of rapid pathogen ID and AST can provide clinicians with evidenced-based information to start patient-specific antimicrobial treatment only when necessary. Even short- term alterations in the use of antibiotics have been found to favorably impact the antibiotic resistance profiles. Furthermore, such platform may be useful to expedite screening of novel class of antibiotics. In this proposal, we will leverage our ongoing efforts to develop an integrated diagnostic biochip for rapid pathogen identification (U01 AI082457) by developing a complementary rapid antimicrobial susceptibility testing (RAST) biochip. This proposed study will utilize high aspect ratio, gas permeable microchannels to obtain optimal conditions for rapid phenotypic assessment of bacterial growth and electrokinetic (EK) sample preparation techniques for on chip matrix management, and develop an electrochemical-based RAST fluidic cartridge to obtain antimicrobial susceptibility assessment from confirmed positive patient populations in 90 minutes. The ultimate goal of the AST development is to leverage the advancement of the established microfluidic cartridge technology and the phenotypic assays developed among all key personnel in the assembled team to establish a comprehensive understanding of not only just the urine specimen but also other body fluids. The overall focus of Aim 1 is to characterize the physical properties of the specimen matrix with various impedance analyses and provide a controllable approach to minimize the matrix effect with electrokinetic trapping. By assessing the impedance mapping of each specimen to be tested, a customized electrokinetic sample preparation will be applied to obtain the maximum extraction efficiency instead of using a universal condition for a wide range of specimen conditions. The outcome of the proposed Aim 1 will provide comprehensive impedance mapping of 98% of urine specimens with impedance analysis and this information will be linked to the optimal EK manipulation conditions to be developed in Aim 1. The passing criteria of Specific Aim 2 is to achieve 100% agreement comparing to urine culture with the microfluidic cartridge and associated control system in 90 minutes compared to urine culture. PHS 398/2590 (Rev. 11/07) Page 1 Continuation Format Page PUBLIC HEALTH RELEVANCE: The absence of definitive microbiological diagnosis at the point of care has led to over- and misuse of antibiotics. We propose to develop a biochip-based rapid AST by utilizing high aspect ratio, gas permeable microchannels for rapid phenotypic assessment of bacterial growth, electrokinetic (EK) sample preparation techniques for on chip matrix management, and develop an electrochemical-based RAST fluidic cartridge to obtain antimicrobial susceptibility assessment from infected urine samples in 90 minutes. PHS 398/2590 (Rev. 11/07) Page 1 Continuation Format Page