Approaching the post-antibiotic era: phage therapy current practices and future horizons

Bacteriophages (phages) are the viral predators of bacteria. Their ability to infect and kill bacterial strains has been harnessed for use in clinical practice for more than a century, but their development stalled for decades in many regions. Now, in the face of increasingly complex bacterial infections that fail conventional therapeutic options, and the growing global threat of antibiotic resistance, interest in phage therapy has resurged. Data evaluating the impact of phage therapy via clinical trials are steadily increasing, but remain sparse. Yet, an ever-growing number of case reports and case series highlights the potential of phage therapy to make a positive impact in the battle against antimicrobial resistance and difficult-to-treat bacterial infections. In this review, we summarize the available data describing the clinical utility of phage therapy, highlight infectious indications where phage therapy shows strong potential, and call attention to disease states where the benefits of phage therapy, as it is practiced today, are less certain. Furthermore, we note areas where there is a crucial need for additional research and propose how scientists and clinicians can work together to design and carry out the preclinical and clinical studies that will take phage therapy into its next century.