The Yersiniabactin-Associated ATP Binding Cassette Proteins YbtP and YbtQ Enhance Escherichia coli Fitness during High-Titer Cystitis
TheYersiniahigh-pathogenicity island (HPI) is common to multiple virulence strategies used byEscherichia colistrains associated with urinary tract infection (UTI). Among the genes in this island areybtPandybtQ, encoding distinctive ATP binding cassette (ABC) proteins associated with iron(III)-yersiniabactin import inYersinia pestis. In this study, we compared the impact ofybtPQon a modelE. colicystitis strain duringin vitroculture and experimental murine infections. AybtPQ-null mutant exhibited no growth defect under standard culture conditions, consistent with nonessentiality in this background. A growth defect phenotype was observed and genetically complementedin vitroduring iron(III)-yersiniabactin-dependent growth. Following inoculation into the bladders of C3H/HEN and C3H/HeOuJ mice, this strain exhibited a profound, 106-fold competitive infection defect in the subgroup of mice that progressed to high-titer bladder infections. These results identify a virulence role for YbtPQ in the highly inflammatory microenvironment characteristic of high-titer cystitis. The profound competitive defect may relate to the apparent selection ofYersiniaHPI-positiveE. coliin uncomplicated clinical UTIs.