METABOLIC ASSESSMENT OF ANTI-MICROBIAL SUSCEPTIBILITY WITHIN ONE CELL CYCLE

Project Summary The increasing emergence of antimicrobial-resistant bacteria/fungi has become a growing global threat dueto the misuse and overuse of antimicrobial drugs. In order to combat infections and reduce anti-microbialresistance, it is essential to detect and characterize bacterial/fungal susceptibility to antimicrobial in the earlystages of infections to reduce the inappropriate use of antimicrobial drugs and the death rate. To address thisurgent medical condition, it is critical to rapidly and accurately determine the antimicrobial susceptibility ofbacteria/fungi so that optimal therapy drugs can be prescribed early in the disease process. Conventionalmethods for antimicrobial susceptibility testing, such as agar plates and broth dilution assays, detect phenotypicresistance based on bacterial/fungal growth in the presence of antimicrobial drugs being tested. A majorlimitation of these methods is that they are based on culture and require at least 16 to 24 h to conduct. Toaddress this unmet need, a microsecond-scale stimulated Raman spectroscopic imaging platform is proposedto enable in situ detection of a single bacterium in complex environment at sub-micron resolution and earlydetermination of its response to an antimicrobial drug. An interdisciplinary team will conduct the proposed study.Dr. Ji-Xin Cheng (PI) is an inventor and leading expert in coherent Raman scattering microscopy. Dr. MohamedSeleem (co-PI) is a DVM-scientist with broad expertise in infectious diseases and microbiology. Dr. Ryan F.Relich (consultant), Medical Director of the Indiana University Health Clinical Virology and Serology Laboratories,has extensive experience in clinical diagnosis of infectious diseases. The team?s central hypothesis thatmicrosecond-scale coherent Raman spectroscopic imaging will enable in situ analysis of single microbial cellsenriched directly from a clinical sample (whole blood). To test this hypothesis, the team will demonstrate fastdetermination of antimicrobial response through microsecond-scale stimulated Raman imaging of metabolicactivity in a single living bacterium (aim 1), develop a microsecond-scale broadband stimulated Ramanspectroscopic microscope for label-free discrimination of bacteria and determination of anti-microbialsusceptibility (aim 2), and demonstrate early detection and fast antimicrobial susceptibility profiling of fungalinfections (aim 3). The proposed rapid AST method works for bacteria/fungi in complex environment and at thesingle cell level. Therefore, long-time specimen culture and subculture to get bacterial/fungal isolate can beavoided. The characteristics of this approach offer a significant advancement over current approaches fortreatment of bacterial/fungal infections.