In Vitro Reversal of Escherichia coli Quiescence by Catechol-Containing Polyphenols and Phenolic Acids Across Multiple Strains

Urinary tract infections (UTIs) are common and create significant clinical challenges. Most UTIs are caused by uropathogenic Escherichia coli (UPEC) and affect 50 to 70% of women at some point in their lives. Of this population, 25% will have a recurrent urinary tract infection (rUTI) within 3 to 12 months of the first episode. High rates of rUTIs may occur because UPEC can enter a non-proliferative or quiescent state within the urothelium of the bladder. This state allows UPEC to evade the host’s immune response and antibiotic treatment. We utilized a library of plant extracts derived from the URI Heber W. Youngken Jr. Medicinal Garden to determine if they reversed UPEC quiescence with a novel in vitro quiescence assay using the classic UPEC endemic lineage ST73 strain CFT073. We found an overall active extract hit rate of 69% (79/114 active) and that active extracts contained high levels of polyphenolic compounds. Further testing showed that polyphenols with adjacent hydroxyl groups on a benzene ring (catechol moiety) were the most effective and potent in reversing quiescence. The ability to reverse quiescence was also linked to the compound’s ability to bind iron (e.g., epigallocatechin gallate and rosmarinic acid were the most potent reversing agents—0.1 mM—and they both had the strongest iron-binding activity as determined via CAS assay). These findings reveal a new class of metabolites that can reverse quiescence in UPEC strains.