By Marco Estrella, Natalie Fox

Faculty Mentor: Dr. Swati Agrawal

Abstract

INVESTIGATING PHAGE-ANTIBIOTIC SYNERGY IN THE TREATMENT OF TWO STRAINS OF BACILLUS CEREUS.  Marco Estrella and Natalie Fox. University of Mary Washington.  Inflammatory use and poor stewardship of antibiotics has contributed to the rise of antimicrobial resistance, which has become a leading public health threat. Bacteriophages, commonly referred to as phages, are specialized viruses that selectively infect specific bacterial strains. Phages have resurged as a valuable tool to combat antibiotic resistance. This research focuses on two strains of B. cereus (a common source of food poisoning), ATCC 11778 and ATCC 14579. The phages Atlee, Azalea, FreightTrain, Grumio, and JackRabbit, discovered at UMW and initially isolated on the non-pathogenic species Bacillus thuringiensis ssp. Kurstaki, posses the potential to infect Bacillus cereus. Our research contains two main focuses. To evaluate the effect that each phage has on either strain independently, then to evaluate the synergistic effects of a phage-antibiotic cocktail on those strains. The antibiotics we utilized were ciprofloxacin (inhibits DNA replication via inhibition of DNA topoisomerase and DNA gyrase) and vancomycin (targets cell wall synthesis). Vancomycin has some potential for the development of resistance, as seen in previous iterations of this project. We have experimentally determined the percent inhibition for each mode of treatment, antibiotics and phages independent of each other and then in combination. Our preliminary data demonstrates an encouraging increase in inhibition of certain phage-antibiotic combinations, indicating a positive synergy between the two therapies. Author Contact: mestrell@mail.umw.edu