Defining a Molecular Signature of Uropathogenic Escherichia coli

项目总结

PROJECT SUMMARY Urinary tract infections (UTIs) are among one of the most common bacterial infections, afflicting 50% of women at least once in their lifetime. Approximately 30% of these women will experience a recurrent infection. Escherichia coli is the most common cause and is responsible for 75% of these infections. Bacteria in the urine, bacteriuria, is a spectrum of clinical presentations, ranging from asymptomatic (ASB), to severe symptoms(such as bacteremia). Unlike diarrheagenic E. coli, UPEC do not have a discrete genetic factor to use for diagnostic purposes. This creates a bottleneck in diagnostics when discerning an asymptomatic urocolonizer from a pathogenic isolate. This is particularly challenging for patient groups such as the elderly or disabled who are unable to communicate the presence of symptoms. There is a significant need to identify a diagnostic molecular signature of UPEC. While there is no discrete gene that defines UPEC, we have previously shown a metabolic signature that does differentiate ASB and cystitis isolates. Many of these metabolites are associated with purine metabolism. While it is known that purine biosynthesis is implicated in the pathogenesis of several bacterial pathogens, the role of purine salvage remains largely unknown. The goal of this proposal is to identify a molecular signature for UPEC. To identify potential areas of focus, we first assessed how the nucleotide intermediate, hypoxanthine, is taken up over time. Our preliminary data show ASB isolates uptake hypoxanthine faster than cystitis isolates. The overarching hypothesis of this project is that subtle genomic features dictate the regulation of purine metabolism, constituting a defining and diagnostic genetic signature for UPEC. To test this hypothesis, I will use transcriptomics, proteomics, and computational genomics to assess the potential of purine metabolism as a molecular signature. Experiments in Aim 1 will investigate the roles of hypoxanthine salvage during a UTI in a well-defined murine model. I will explore differences in membrane proteins and transcript abundance of known genes involved in purine metabolism throughout infection, and use targeted comparative genomics to look for variations in the gene operons of these pathways. In Aim 2, I will take a broad, unbiased genomics approach to identify other potential genomic regions that could constitute a molecular signature. I will utilize isolates banked at our microbial biobank, linked to the de-identified medical record, and subject them to sequencing and a genome-wide association study (GWAS). Collectively, these data will provide a rigorous definition of UPEC, while investigating a potential molecular signature. Additionally, these studies will define the role of purine salvage in UPEC pathogenesis. The proposed work will have broad implications in purine metabolism in bacterial pathogenesis as well as the novel use of microbial GWAS with patient- phenotypes.