Identification and development of antimicrobial peptoids effective against cross-kingdom biofilms Project Summary The purposed work focuses on identifying antimicrobial compounds targeting cross-kingdom biofilms generated by Candida albicans and bacteria through high-throughput screening of a one bead one compound combinatorial library. C. albicans is the third most common source of hospital acquired infections and the primary source of hospital acquired fungal infections, with high rates of morbidity and mortality. C. albicans often forms cross-kingdom polymicrobial biofilms with other infectious microbes. These cross-kingdom interactions can be synergistic and result in unique quorum-sensing that causes increased drug resistance. Antimicrobial drugs that treat both the fungal and the bacterial infections within a complex, synergistic biofilm would provide a valuable therapeutic option to those dealing with deadly hospital acquired cross-kingdom biofilm infections. Once such option could be antimicrobial peptoids. Peptoids are a useful class of peptidomimetics due to ease of synthesis, increased bioavailability, and decreased protease recognition compared with peptides. Our lab and others have demonstrated the antimicrobial efficacy of peptoids against both bacterial and fungal pathogens. Additionally, reports demonstrate modest efficacy of antimicrobial peptoids against both monospecial and cross-kingdom biofilms. However, the low throughput nature of these antimicrobial peptoid reports limits the compound chemical diversity and biofilm species variety they can explore. The overall goal of this proposal is to identify antimicrobial peptoids effective against C. albicans/bacterial cross-kingdom biofilms through the adaption and use of our previously developed PLAD high-throughput assay. Specific work proposed here will include the synthesis of several combinatorial peptoid libraries and screening of these libraries using our high-throughput Peptoid Library Agar Diffusion (PLAD) assay with subsequent testing to evaluate antibiofilm activity. Additionally, we will also adapt our PLAD assay to screen peptoid libraries against mature, established biofilms to directly generate peptoids with antibiofilm activity. Antibiofilm compounds rapidly identified using these techniques will be resynthesized and their broad antibiofilm activity and preliminary cytotoxicity evaluated using traditional methods to generate lead compounds. Successful completion of this work will result in antibiofilm peptoids that can be further developed into therapeutic options for individuals dealing with deadly cross-kingdom biofilm infections on wounds, prosthetics, and other surfaces.

Public Health Relevance

Cross-kingdom biofilms are a common infectious scenario that are difficult to treat due increased drug resistance within the biofilm. The proposed research seeks to identify and develop peptoid compounds that kill microbes living in these biofilms. Successful completion of this work will result in improved treatment options for individuals dealing with these deadly infections.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Small Research Grants (R03)
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Special Emphasis Panel (ZRG1)
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Xu, Zuoyu
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Middle Tennessee State University
Schools of Arts and Sciences
United States
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