Project Summary
Catheter-associated urinary tract infection (CAUTI) is the leading cause of secondary nosocomial bloodstream
infections. Urease-producing organisms such as Proteus mirabilis are common causes of CAUTI and
associated with numerous complications. Urease hydrolyzes urea to ammonia, which raises the urine pH and
causes precipitation of ions into crystals, ultimately leading to catheter encrustation and blockage and urinary
stone formation and increasing the risk of bacteremia, sepsis and death. The only urease inhibitor approved by
the Food and Drug Administration (FDA), acetohydroxamic acid (AHA), shows efficacy in preventing urinary
stone formation but has severe side effects that limit its clinical use. Therefore, alternative strategies are
needed for targeting bacterial urease activity to prevent catheter encrustation and stone formation. In patients
with long-term indwelling catheters, CAUTI is often polymicrobial. As demonstrated in our prior publications
and preliminary data, we found that common constituents of polymicrobial CAUTI secrete molecules that
modulate P. mirabilis urease activity and infection severity. We therefore performed untargeted global
metabolomics analysis on cell-free supernatants of urease-modulating bacterial strains and identified 36
candidate urease dampening metabolites. We validated the activity of four compounds: histamine (CAS 51-45-
6), leucylglycine (CAS 686-50-0), phenylpyruvate (CAS 156-06-9) and imidazole lactate (CAS 14403-45-3).
Our preliminary data suggests that leucylglycine and imidazole lactate dampen urease activity, at least in part,
by acting directly on the urease active site. In contrast, histamine and phenylpyruvate appear to indirectly
inhibit urease activity through an uncharacterized mechanism. The goal of this NRSA F30 proposal is to
determine the mechanism of action of urease modulation and conduct pre-clinical assessment of the
therapeutic potential of these dampening compounds. Aim 1 will determine the mechanism of indirect urease
modulation for histamine and phenylpyruvate and explore whether compounds of different mechanisms of
action have synergistic effects on urease activity when administered in combination against a panel of urease-
producing pathogens. Aim 2 will assess the translational potential of dampening compounds for preventing
Foley catheter encrustation, crystalline biofilm formation, and blockage. The experiments outlined in this
proposal will provide a framework for harnessing polymicrobial interactions for drug discovery and the
development of novel therapeutics to prevent CAUTI associated morbidity and mortality. This work will take
place at the Jacobs School of Medicine and Biomedical Sciences in the laboratory of Dr. Chelsie Armbruster,
who is an expert in CAUTI and microbial pathogenesis research. The training plan is tailored for my
development as a physician-scientist in the field of infectious disease, and includes mentoring by successful
physician-scientists and clinical preceptorships in infectious disease and internal medicine.
