Phage Therapy in Bacterial Infection

Phage therapy has proven to be an effective method to control bacterial infection [1] and it has been successfully applied for the treatment of Shigella dysenteriae infections in children. The phage therapy approach is an effective method for controlling multidrug-resistant bacteria. Félix d’Herelle discovered phages as a lytic agent active on dysentery bacteria exactly 100 years ago [2]. When working on cholera in India, d’Herelle observed that mortality declines during an epidemic. Studying stool phages, he linked death and recovery from disease with the absence or presence, respectively, of virulent vibriophages in the patients [3]. Shigellosis, an infectious diarrheal disease, is caused by the enteric pathogen Shigella. It is a major worldwide health burden and causes nearly 164.7 million cases and over a million deaths every year, most of them occurring in developing countries [4]. Bacteriophages (phages) are viruses that infect bacteria. With many species of bacteria becoming resistant to antibiotics, phages are reemerging as an attractive alternative and have already been used to combat a wide variety of bacterial infections [5]. One of the first bacteriophages ever isolated was a Shigella phage, discovered by Felix d’Herelle in 1917 [6,7], which was subsequently shown to cure children suffering from severe S. dysenteriae infection [8]. However, relatively few studies on the isolation or characterization of Shigella phages have been performed since then. Information for only ∼35 Shigella phages has been deposited in public databases, and detailed studies of these phages are sparse. By contrast, over 400 Escherichia and Salmonella phages are readily available, some of which, such as φX174, P22, λ, and T4, have been used as model systems for decades. As the problem of antibiotic resistance becomes ever more acute, a number of scientists and clinicians are looking again at bacteriophages as a therapeutic option in the treatment of bacterial infections.