With the global rise in antimicrobial resistance, there has been a renewed interest in the application of therapeutic phages to treat bacterial infections. Therapeutic phage monitoring (TPM) is proposed as an essential element of phage therapy (PT) protocols to generate data and fill knowledge gaps regarding the in vivo efficacy of therapeutic phages, patients' immune responses to PT, and the wider ecological effects of PT. By monitoring phage concentrations in blood and tissues, together with immune responses and possible ecological changes during PT, TPM may enable the optimization of dosing and the implementation of precision medicine approaches. Furthermore, TPM can validate diagnostic surrogates of efficacy, direct research efforts, and establish quality assurance indicators for therapeutic phage products. Thus, TPM holds great potential for enhancing our understanding of the multidirectional phage-bacteria-host interactions and advancing "best practice" PT, ultimately improving patient care.
Keywords: bacteria; bacteriophage; infectious disease; phage therapy; therapeutic phage monitoring.
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