Evaluation of Novel Antimicrobial Peptides against Pseudomonas Aeruginosa Strains PA14 and PA01
Discipline: Biological Sciences
Subcategory: Microbiology/Immunology/Virology
Session: 1
Room: 7 - Embassy F
Amber Grace - Alabama State University
Co-Author(s): Rajnish Sahu, Alabama State University, Montgomery, AL; Donald R. Owen, Owen Biosciences Inc., Baton Rouge, LA; Vida A. Dennis, Alabama State University, Montgomery, AL
Pseudomonas aeruginosa is a ubiquitous, gram-negative bacterium frequently responsible for hospitalized-acquired infections that lead to increased mortality for immunocompromised patients. The World Health Organization has designated P. aeruginosa as a highly resistant pathogen in critical need of novel therapeutics. Antimicrobial peptides (AMPs) are attractive options to combat this crisis, as their ability to attack multiple low-affinity bacteria results in lower selective pressure for the emergence of resistant strains [1]. However, the highly adaptable and genetically plastic P. aeruginosa has complicated effective drug discovery. P. aeruginosa has proven to show discordant susceptibility and resistance to the same therapeutics screened in the recommended antimicrobial susceptibility testing (AST) media Mueller-Hinton broth and in host-mimicking conditions modeled by cell culture media with serum. This is problematic as recent studies have found therapeutic screening against an array of gram-positive and gram-negative bacteria in host-mimicking conditions to be more predictive of clinical success [2]. Additionally, novel therapeutics that target virulence have required in vitro conditions more like the biological host to produce reliable results [3]. In our present study, we hypothesize that proprietary AMPs (OB 1105 and OB 1111) can address the challenges to P. aeruginosa treatment through inhibitory, bactericidal, and anti-virulence activity. We used the two most common P. aeruginosa reference strains, PA14 and PAO1, in our study. Our results showed that the minimum inhibitory concentrations (MICs) of both OB 1105 and 1111 against P. aeruginosa strains in AST conditions were 16 µg/mL against PA14 and 32 µg/mL against PAO1. These MICs increased in host-mimicking Dulbecco’s Modified Eagle’s Medium (DMEM) supplemented with either heat-inactivated fetal bovine or human serum, suggesting that these AMPs may be more suitable for topical application where serum is unable to inhibit activity. Since our previous work revealed differential expression of P. aeruginosa PA14 virulence factors and activity in AST and host-mimicking conditions, we will further evaluate the anti-virulence potential of both AMPs at sub-inhibitory concentrations through polymerase chain reaction (PCR), motility, and chemotaxis studies.
Funder Acknowledgement(s): This research was supported by the National Science Foundation (NSF) HBCU-UP (HRD-1911660) and the National Institute of Health (NIH)-NIGMS-RISE (1R25GM106995-01) grants and the Ph.D. Program in Microbiology at Alabama State University.
Faculty Advisor: Vida A. Dennis, vdennis@alasu.edu
Role: I designed and performed the experiments and analyzed the results.