By 2050 antimicrobial resistance (AMR) will kill 10 million people annually, more than cancer, at a cumulative global cost of US$100 trillion. Bacteriophages ("phages", viruses that infect and may kill bacteria) in the pre-antibiotic era were widely used as treatments for bacterial infection, and were regarded as effective and extremely safe. With the looming AMR crisis, there is resurgent interest in using phages to treat bacterial infections. There are many clinical infection settings in which phages have potential as a treatment. We have examined phages against Staphylococcus aureus, with a view to using these in treatment of chronic rhinosinusitis (CRS), which afflicts about 15% of people, and is often associated with infection of the sinuses with S. aureus. Direct introduction of phages into the sinuses could be a treatment option for this condition. We have used phages against S. aureus in a sheep model, and have shown them to be safe and effective in treating S. aureus rhinosinusitis in this model. We have undertaken a phase I clinical trial of phage product AB-SA01, made by our commercial partner AmpliPhi Biosciences, which is a cocktail of 3 phages, all myoviridae, targeting S. aureus. There were 9 subjects in this trial, each with S. aureus CRS. Phages were instilled into the sinuses daily via the nose, for up to 2 weeks. No serious adverse effects were noted. There is preliminary data consistent with AB-SA01 reducing S. aureus infection, and in 2/9 patients S. aureus was eradicated from the sinuses.
A previously identified limitation of phages is their need to be matched with the serotype of the infecting pathogen. Our surveys of the phage susceptibility of bacterial isolates from patients show that this issue is addressed by use of phage cocktails which lyse ca. 95% of S. aureus isolates from Adelaide clinics.