BACTERIAL SECONDARY METABOLITES DISTINGUISH COMMENSAL AND PATHOGENIC E COLI

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Project Summary: Genomic and transcriptional data suggest a prominent role for bacterial iron acquisition during urinary tract infection (UTI) pathogenesis. One means by which Escherichia coli, the major cause of UTI, obtain iron from their surrounding is secretion of small iron-chelating molecules called siderophores. While all E. coli are capable of secreting an ancestral siderophore called enterobactin, many clinical strains have acquired genes for secretion and uptake of chemically distinct siderophores, which may have a special role in pathogenesis. We have used the LCQ-DECA to develop an LC-MS/MS (MRM) assay for qualitative and quantitative studies of siderophore production between E. coli strains. This assay uses stable isotope labeling to compare gut and urinary tract isolates of E. coli obtained through a collaboration with clinical researchers at the University of Washington's Urinary Tract Infection Research Center. From this study, we have obtained evidence suggesting that urinary pathogens are often selected from available gut strains based on their ability to produce the highest levels of two specific siderophores. This assay will be used to identify particularly virulent E. coli strains in initial clinical microbiology studies. With more sensitive instrumentation, we will follow up on preliminary in vivo data to adapt this assay to perform in vivo diagnostics through detection of virulence-associated siderophores directly from patient urine. We intend to use the mass spectrometric approaches developed here to begin pilot studies on in vivo microbiologic diagnostics for clinical use.