The Yersiniabactin-Associated ATP Binding Cassette Proteins YbtP and YbtQ Enhance Escherichia coli Fitness during High-Titer Cystitis

Abstract

ABSTRACT The Yersinia high-pathogenicity island (HPI) is common to multiple virulence strategies used by Escherichia coli strains associated with urinary tract infection (UTI). Among the genes in this island are ybtP and ybtQ , encoding distinctive ATP binding cassette (ABC) proteins associated with iron(III)-yersiniabactin import in Yersinia pestis . In this study, we compared the impact of ybtPQ on a model E. coli cystitis strain during in vitro culture and experimental murine infections. A ybtPQ -null mutant exhibited no growth defect under standard culture conditions, consistent with nonessentiality in this background. A growth defect phenotype was observed and genetically complemented in vitro during iron(III)-yersiniabactin-dependent growth. Following inoculation into the bladders of C3H/HEN and C3H/HeOuJ mice, this strain exhibited a profound, 10 6 -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 of Yersinia HPI-positive E. coli in uncomplicated clinical UTIs.