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Bacteriophages are the most abundant biological entities on earth, and it is estimated that phage predation reduces the global bacterial population by half every 48 h. Bacteriophages also drive adaptive evolution in their bacterial hosts both through predator-prey interaction dynamics and via adaptive impacts of lysogeny. Despite predating the discovery of antibiotics by several decades, bacteriophage therapy was largely supplanted by antibiotics and their use in Western medicine declined. However, bacteriophages have several characteristics that make them potentially attractive next-generation therapeutic agents, with several benefits over conventional antibiotics. Phages are highly specific and, therefore, do not disturb normal flora; replicate in their host, facilitating effective treatment by delivery of a low-phage dose; are amplified at the site of infection; and are capable of rapid adaptation to combat emergence of bacterial resistance. Bacteriophages, therefore, hold significant promise as a therapeutic approach in the face of widespread antibiotic resistance. In addition, bacteriophages are sources of biochemical reagents, which are of value in modern molecular biology and as anti-infective chemotherapeutics in their own right.
Bacteriophages in anti-infective therapy
Martha Clokie (University of Leicester, UK) presented recent work on the nature, isolation and exploitation of phages for pathogenic anaerobes, in particular Clostridium difficile . C. difficile (of which there are over 350 ribotypes) is a major causative organism in antibiotic-associated diarrhea and pseudomembranous colitis. Outbreaks of C. difficile infections are common in industrialized nations and are associated with significant morbidity and mortality. Furthermore, such outbreaks impose a significant financial burden on healthcare providers, yet remain difficult to rapidly diagnose and treat effectively. The work of Clokie and colleagues has revealed that temperate phage carriage among infected individuals is common and may contribute to virulence [1]. Her group has spearheaded the search for lytic C. difficile phages, which may have diagnostic and therapeutic value, and has led to the establishment of a panel of 20 lytic bacteriophages, which target clinically relevant, dominant ribotypes of C. difficile commonly associated with infection outbreaks in UK hospitals. This phage library has been extensively characterized according to their morphology, genome sequence, infection parameters and host range using a number of in vitro and in vivo methods. These bacteriophages are likely to be of significant therapeutic potential in the management of such outbreaks and,...