Phage therapy to treat unresponsive infections: A primer for the clinical microbiology laboratory staff

With the increase in antimicrobial resistance and subsequent need for alternatives to traditional antibiotics, phage therapy (PT) has gained a renewed interest. Much like antibiotics, bacteriophages or simply phages, have shown promise in eradicating bacterial infections; however, their fundamental differences require specific laboratory protocols and practices. As bacterial-specific viruses, they must be detected, replicated, and purified for safety and efficacy. The narrow spectrum of activity of phages provides a targeted approach to infection but also necessitates expansive libraries and susceptibility testing to match phages to bacteria. Such testing is not standardized, complicating both research and clinical efforts. This review then provides a background on PT in the clinical microbiology laboratory and an overview of such protocols and practices specific to PT, such as classic susceptibility testing methods and updated approaches. Also covered are the challenges and future directions for the field, as well as resources for clinical and research laboratory personnel.