By Anna Reed

Faculty Mentor: Swati Agrawal

Abstract

To address the rising threat of antimicrobial resistance to public health, this study explores the use of bacteriophages as alternative treatment strategies when combined with traditional antibiotics. Bacteriophages are viruses that infect bacteria with remarkable specificity. Phages have re-emerged as promising tools to combat antibiotic resistance in Bacteria. Our research investigated the potential of phages to reduce the minimum inhibitory concentration (MIC) of antibiotics in in vitro assays. The phages Atlee, Azalea, FreightTrain, Grumio, and JackRabbit were discovered by students at the University of Mary Washington and isolated from Bacillus thuringiensis ssp. kurstaki. Given the potential host range of these phages within the Bacillus genus, we selected two pathogenic strains of Bacillus cereus (ATCC 11778 and ATCC 14579) for further analysis. The antibiotics tested were ciprofloxacin, which inhibits DNA replication by targeting DNA topoisomerase and gyrase, and vancomycin, which interferes with cell wall synthesis. Inhibition was assessed using broth microdilution assays under three treatment conditions: antibiotics alone, phages alone, and phage–antibiotic combinations. Preliminary data indicate enhanced inhibition in specific phage–antibiotic pairings, suggesting a synergistic interaction between the two therapies. Ongoing studies aim to define the mechanics of this synergy and evaluate its applicability across a wider range of pathogenic bacteria.