Lifting the mask: identification of new small molecule inhibitors of uropathogenic Escherichia coli group 2 capsule biogenesis.

Carlos C Goller,Subramaniam Ananthan,Frank Schoenen,Steven A Rogers,Brooks E Maki,Lynn Rasmussen,James W Noah,Melinda Sosa,N Miranda Nebane,Patrick Porubsky,Benjamin Neuenswander,Nichole A Tower,Mehreen Arshad,Carrie W Evans,Patrick C Seed,E Lucile White,Mikael Skurnik

doi:10.1371/journal.pone.0096054

Carlos C Goller, Subramaniam Ananthan + Show 15 more

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https://doi.org/10.1371/journal.pone.0096054

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Abstract

Uropathogenic Escherichia coli (UPEC) is the leading cause of community-acquired urinary tract infections (UTIs), with over 100 million UTIs occurring annually throughout the world. Increasing antimicrobial resistance among UPEC limits ambulatory care options, delays effective treatment, and may increase overall morbidity and mortality from complications such as urosepsis. The polysaccharide capsules of UPEC are an attractive target a therapeutic, based on their importance in defense against the host immune responses; however, the large number of antigenic types has limited their incorporation into vaccine development. The objective of this study was to identify small-molecule inhibitors of UPEC capsule biogenesis. A large-scale screening effort entailing 338,740 compounds was conducted in a cell-based, phenotypic screen for inhibition of capsule biogenesis in UPEC. The primary and concentration-response assays yielded 29 putative inhibitors of capsule biogenesis, of which 6 were selected for further studies. Secondary confirmatory assays identified two highly active agents, named DU003 and DU011, with 50% inhibitory concentrations of 1.0 µM and 0.69 µM, respectively. Confirmatory assays for capsular antigen and biochemical measurement of capsular sugars verified the inhibitory action of both compounds and demonstrated minimal toxicity and off-target effects. Serum sensitivity assays demonstrated that both compounds produced significant bacterial death upon exposure to active human serum. DU011 administration in mice provided near complete protection against a lethal systemic infection with the prototypic UPEC K1 isolate UTI89. This work has provided a conceptually new class of molecules to combat UPEC infection, and future studies will establish the molecular basis for their action along with efficacy in UTI and other UPEC infections.

Highlights

Urinary tract infection (UTI) is the second leading infection in humans [1] and the most common bacterial infection in the ambulatory care setting in the United States, accounting for up to 8.6 million health care visits in 2007 [2]
The K1 encapsulated strain of uropathogenic E. coli UTI89 was grown in a 1,536-well plate format in the presence of 50 mM compounds
Compounds with no effect on capsule biogenesis allowed the growth of organisms with an intact capsule that were subsequently lysed by the addition of the K1F phage

Summary

Introduction

Urinary tract infection (UTI) is the second leading infection in humans [1] and the most common bacterial infection in the ambulatory care setting in the United States, accounting for up to 8.6 million health care visits in 2007 [2]. Twenty-five to forty percent of first-time community-acquired UTIs are followed by recurrences caused by the same clone of UPEC [3,6,7]. Among all UTI cases, approximately 40-times more are treated in the outpatient setting relative to inpatient care [7]. Rising antibiotic resistance is a serious problem affecting the clinical utility of the drugs commonly available for outpatient treatment of UTIs (e.g., [10]).

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