Blocking Yersiniabactin Import Attenuates Extraintestinal Pathogenic Escherichia coli in Cystitis and Pyelonephritis and Represents a Novel Target To Prevent Urinary Tract Infection

Abstract

The emergence and spread of extended-spectrum beta-lactamases and carbapenemases among common bacterial pathogens are threatening our ability to treat routine hospital-and community-acquired infections. With the pipeline for new antibiotics virtually empty, there is an urgent need to develop novel therapeutics. Bacteria require iron to establish infection, and specialized pathogen-associated iron acquisition systems like yersiniabactin, common among pathogenic species in the family Enterobacteriaceae, including multidrug-resistant Klebsiella pneumoniae and pathogenic Escherichia coli, represent potentially novel therapeutic targets. Although the yersiniabactin system was recently identified as a vaccine target for uropathogenic E. coli (UPEC)-mediated urinary tract infection (UTI), its contribution to UPEC pathogenesis is unknown. Using an E. coli mutant (strain 536⌬fyuA) unable to acquire yersiniabactin during infection, we established the yersiniabactin receptor as a UPEC virulence factor during cystitis and pyelonephritis, a fitness factor during bacteremia, and a surface-accessible target of the experimental FyuA vaccine. In addition, we determined through transcriptome sequencing (RNA-seq) analyses of RNA from E. coli causing cystitis in women that iron acquisition systems, including the yersiniabactin system, are highly expressed by bacteria during natural uncomplicated UTI. Given that yersiniabactin contributes to the virulence of several pathogenic species in the family Enterobacteriaceae, including UPEC, and is frequently associated with multidrug-resistant strains, it represents a promising novel target to combat antibiotic-resistant infections.W idespread and increasing antibiotic resistance among bacterial pathogens that cause some of our most common health care-associated and community-acquired infections is jeopardizing our ability to prevent and treat routine infectious diseases (1). Two pathogens of particular concern are uropathogenic Escherichia coli (UPEC), which causes the majority (80%) of uncomplicated urinary tract infections (UTI) (2), and Klebsiella pneumoniae, a frequent cause of hospital-acquired pneumonia and UTI (3). Without adequate treatment, both UPEC and K. pneumoniae can breach epithelial and endothelial barriers to gain access to the bloodstream, causing life-threatening bacteremia (4). E. coli rates of resistance to fluoroquinolones and third-generation cephalosporins now exceed 50% in 5 of 6 global regions, and similar resistance rates were reported for K. pneumoniae worldwide (5). Unfortunately, the treatment of severe infections caused by these species must rely on carbapenems, the last resort to treat severe community-and hospital-acquired infections (6). Not only are these antibacterial compounds more expensive and less available in resource-constrained settings, but their extended use contributes to the spread of carbapenem-resistant Enterobacteriaceae (CRE), a serious global public health concern (7).Increasing rates of antimicrobial resistance and limited new therapeut...

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

“…A recent study using a fyuA-deficient UPEC strain found that it had a competitive defect in the bladder weaker than that observed for the ybtPQ-deficient UPEC strain in the present study. In contrast, the defect in infections with a single strain was somewhat more pronounced for fyuA mutants than ybtPQ mutants (29,(47)(48)(49)(50). A previous study using a tonB-deficient UPEC strain yielded results similar to those obtained with the fyuA mutant (51).…”

“…The overall expression of the yersiniabactin system can be inferred by evidence of yersiniabactin biosynthesis as well as serological and transcriptional evidence of ybtP, ybtQ, and fyuA expression during mouse and human cystitis (17,(27)(28)(29). Beyond UTIs, ybtPQ mutants of Yersinia pestis and Klebsiella pneumoniae exhibit diminished virulence in mouse models of bubonic plague and pneumonia, respectively (14,30).…”

Enterobacteria secrete an inhibitor of Pseudomonas virulence during clinical bacteriuria

“…It is highly prevalent among clinical extraintestinal pathogenic E. coli isolates and is also found with varying frequencies in other Enterobacteriaceae, including the eponymous Yersinia pestis (18). Yersinia HPI genes are highly upregulated during UTI, and Ybt is detectable in patients' urine specimens (12,14,17). Ybt, the recognized product of Yersinia HPI-positive bacteria to date, has been distinguished from other E. coli siderophores by its ability to form stable Cu(II) complexes.…”

“…These results suggest that the early stages of ascending UTI are competitive and favor isolates with specific siderophore profiles. In this and other studies, Ybt, a siderophore encoded by the Yersinia high pathogenicity island (HPI), was associated with urinary tract virulence (7,(13)(14)(15)(16)(17).…”

Uropathogenic enterobacteria use the yersiniabactin metallophore system to acquire nickel

“…Prominent among these is the Yersinia high pathogenicity island (HPI), which encodes the biosynthetic machinery to make the specialized metabolites yersiniabactin (Ybt) and escherichelin (2). Direct mass spectrometric detection of urinary Ybt in UTI patients, serological markers, transcriptional signatures, and experimental infection models all indicate active expression of Yersinia HPI proteins during UTI pathogenesis (3)(4)(5)(6)(7).…”