Infections caused by Enterobacteriaceae, primarily the Gram-negative pathogens Klebsiella pneumoniae and Escherichia coli, are becoming increasingly difficult to treat owing to widespread resistance to several classes of antibiotics including penicillins, cephalosporins, carbapenems, fluoroquinolones and antifolates. Along with resistance, the naturally limited array of agents effective against Gram-negative pathogens and the dearth of antibiotic discovery in the pharmaceutical industry combine to create a critical need for new drug discovery. For the past several years, we have used a structure-based effort to develop a novel series of propargyl-linked antifolates that potently inhibit the essential enzyme dihydrofolate reductase (DHFR) and are effective against Gram-positive and eukaryotic pathogens. Additionally, these compounds show low rates of resistance and have good physicochemical properties. Recently, we have discovered that the propargyl-linked antifolates are potent inhibitors of K. pneumoniae in culture and against K. pneumoniae DHFR. Here, we propose to extend this class of antifolates to become excellent antibiotics against pathogenic Enterobacteriaceae. We propose three specific aims. In the first aim, we will develop inhibitors that are potent and selective inhibitors of K. pneumoniae and E. coli DHFR and potent inhibitors of wild-type and resistant Enterobacteriaceae, such as trimethoprim-, ESBL-, KPC- and NDM1-variants while maintaining low human cell toxicity. In the second aim, we will determine iterative crystal structures of wild-type and trimethoprim-resistant Enterobacteriaceae DHFRs as well as human DHFR, intended to drive the design of potent and selective compounds.
The third aim will focus on studies in animals: an initial stage with a set of potent compounds begins with the evaluation of efficacy against wild-type strains and initial pharmacokinetic parameters. A second stage will evaluate efficacy against a range of phenotypes along with detailed pharmacokinetic/pharmacodynamic parameters. At the end of this proposal we expect to deliver a highly efficacious, orally available antifolate antibiotic against a broad range of Enterobacteriaceae isolates.

Public Health Relevance

The emergence of highly resistant and difficult-to-treat bacterial infections presents a major healthcare issue that affects patients, leading to increased mortality and costs. Of particular importance are the Gram-negative Enterobacteriaceae, especially Klebsiella pneumoniae and Escherichia coli that are causative agents of pneumonia, urinary tract and bloodstream infections. Treatment options for these organisms are very limited and new antibiotics are a priority. This application describes a development of a new series of antibiotics that are effective against Enterobacteriaceae and that work by inhibiting a key enzyme involved in metabolism.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI104841-03
Application #
8960331
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Xu, Zuoyu
Project Start
2013-12-01
Project End
2018-11-30
Budget Start
2015-12-01
Budget End
2016-11-30
Support Year
3
Fiscal Year
2016
Total Cost
Indirect Cost
Name
University of Connecticut
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
614209054
City
Storrs-Mansfield
State
CT
Country
United States
Zip Code
G-Dayanandan, Narendran; Scocchera, Eric W; Keshipeddy, Santosh et al. (2017) Direct Substitution of Arylalkynyl Carbinols Provides Access to Diverse Terminal Acetylene Building Blocks. Org Lett 19:142-145
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Hajian, Behnoush; Scocchera, Eric; Keshipeddy, Santosh et al. (2016) Propargyl-Linked Antifolates Are Potent Inhibitors of Drug-Sensitive and Drug-Resistant Mycobacterium tuberculosis. PLoS One 11:e0161740
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Scocchera, Eric; Reeve, Stephanie M; Keshipeddy, Santosh et al. (2016) Charged Nonclassical Antifolates with Activity Against Gram-Positive and Gram-Negative Pathogens. ACS Med Chem Lett 7:692-6
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Reeve, Stephanie M; Scocchera, Eric W; G-Dayanadan, Narendran et al. (2016) MRSA Isolates from United States Hospitals Carry dfrG and dfrK Resistance Genes and Succumb to Propargyl-Linked Antifolates. Cell Chem Biol 23:1458-1467
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Keshipeddy, Santosh; Reeve, Stephanie M; Anderson, Amy C et al. (2015) Nonracemic Antifolates Stereoselectively Recruit Alternate Cofactors and Overcome Resistance in S. aureus. J Am Chem Soc 137:8983-90

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