Due to the rise of multidrug-resistant infections in humans, phage therapy is gaining renewed attention in Western medicine. Despite the increasing number of publications focussed on the isolation, characterization and in vitro performance of different phages, there is still a lack of concise pre-clinical information to guide the application of phage therapy in clinical practice. Nevertheless, over the last decade, efforts have been made to conduct more detailed studies of the in vivo efficacy of phages. Here, we review the most relevant in vivo studies performed in the last decade covering phage efficacy in both preclinical and clinical trials. We compare different routes of administration, dosage effect and different animal models of distinct types of infections. Moreover, insights into case studies and results from clinical trials are presented. Challenges and limitations of phage use as evidenced by the current state of research are also discussed in order to improve both the trustworthiness and success of the implementation of phage therapy.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, COMPETE 2020 [POCI-01-0145-FEDER-006684] and Projects PTDC/SAU-PUB/29182/2017 [POCI-01-0145-FEDER-029182] and PTDC/CVTCVT/29628/2017 [POCI-01-0145-FEDER-029628]. This work was also supported by BioTecNorte operation [NORTE-01-
0145-FEDER-000004] funded by the European Regional Development Fund under the scope of Norte2020 -
Programa Operacional Regional do Norte. DPP was supported by a FCT grant [SFRH/BPD/116187/2016]. KD is the recipient of the National Science Centre in Poland grant [UMO-2018/29/B/NZ6/01659]. The funding bodies had no role in study design, data collection and analysis, preparation of the manuscript, or the decision to publish.info:eu-repo/semantics/publishedVersio
