Abstract This proposal is for BACLIB, a cost-effective, one hour microbial ID test direct from a clinical specimen or positive blood culture. Microbial ID testing is an essential step to appropriate antimicrobial treatment. Today, positive microbial culture indicates a microbial infection, and subsequent microbial ID testing on cultured samples identifies species. Microbial cultures typically take a day to turn positive. During this period, clinicians must treat patients empirically, delaying appropriate therapy, and increasing the risk of sepsis and other adverse events. We have developed BACLIB, a one-hour test that identifies microbial infections directly from positive blood culture (PBC) or urine specimens. BACLIB measures species-specific microbial membrane lipids: lipid A in Gram-negative bacteria, and analogous lipids in Gram-positive bacteria and fungi. These lipids are abundant, easily extracted, and more sensitively detected and identified than analytes used by current tests. In preliminary results with clinical PBC specimens, BACLIB correctly identified 93% of samples. The only available rapid ID test for PBC correctly identified only 61% of these same samples. Thus, BACLIB offers significant advantages over available tests for positive blood culture. BACLIB shows similar performance direct from urine specimens, where there is currently no approved direct-from-specimen ID test. In this proposal, we develop a prototype clinical assay based on BACLIB. The prototype will be evaluated on clinical and prepared specimens and compared with standard methods. The research approach is as follows: Specific Aim 1: Pathogen ID Direct From Specimen. In this aim we identify pathogens direct from PBC and urine using BACLIB. Specific Aim 2. Quantitation of Pathogens Direct From Urine. In this aim we measure the quantity of pathogens in urine, to determine positive urine specimens, defined by microbial concentration. Specific Aim 3. Polymicrobial Specimens. In this aim we evaluate BACLIB in identifying species in clinical and prepared polymicrobial PBC and urine specimens. Appropriate antimicrobial therapy is essential to effective treatment of bacteriuria and bacteremia, and to prevention and treatment of sepsis. These conditions remain major health problems. Furthermore, in the case of sepsis progression is often rapid, so that a single hour saved in diagnosis time can significantly reduce mortality. Faster tests are therefore needed to save lives.

Relevance to public health: Sepsis, the leading cause of US hospital death, is usually preceded by bacteremia. Sepsis is the most expensive US hospital condition, at $24 billion per year. Bacteremia (bloodstream infection) is itself a growing medical problem. Considering just nosocomial bacteremias in the US, there are 250,000 such cases per year with about 20% mortality. Bacteremia incidence is increasing and mortality remains stubbornly high. Bacteriuria is also a major health problem, affecting millions of people every year and ultimately causing an estimated 25% of sepsis cases each year. This research, if successful, will lead to a new, cost-effective, rapid microbial ID test. In bacteremia and sepsis, speed is life. Sepsis mortality increases every hour effective antibiotic intervention is delayed. This research is thus of substantial potential importance to public health.