*2.9.2 Safety and efficiency of phage therapy*

Galtier et al. [139] infected mice with an adherent-invasive E. coli strain known to be implicated in IBD pathogenesis and administered phage preparation to murine gut sections, living animals, and homogenates of ileal biopsies obtained from CD patients, obtaining a decrease in the colony-forming units of the E. coli strain and a reduction of the clinical picture of dextran sodium sulfate-induced colitis in mice.

Many research studies were not able to find any serious life-threatening adverse effects related to phage treatment [140–142]. A phase I therapy of venous leg ulcers in humans also demonstrated no safety concerns [143]. Another study using transfer of whole viral communities *via* FMT between humans shows that none of the transferred viruses infected human cells [136]. These results highlight the safety of phage therapy, without the development of any serious side effects.

An overview of the current microbial-targeted therapies as well as future treatment approaches for patients with IBD is presented in **Figure 5**.
