  As antibiotic resistance grows more frequent for common bacterial infections,
alternative treatment strategies such as phage therapy have become more widely
studied in the medical field. While many studies have explored the efficacy of
antibiotics, phage therapy, or synergistic combinations of phages and
antibiotics, the impact of virus competition on the efficacy of antibiotic
treatment has not yet been considered. Here, we model the synergy between
antibiotics and two viral types, temperate and chronic, in controlling
bacterial infections. We demonstrate that while combinations of antibiotic and
temperate viruses exhibit synergy, competition between temperate and chronic
viruses inhibits bacterial control with antibiotics. In fact, our model reveals
that antibiotic treatment may counterintuitively increase the bacterial load
when a large fraction of the bacteria develop antibiotic-resistance.
