Phage therapy: past history and future prospects.

Bacterial viruses (bacteriophages, also called "phages") can be robust antibacterial agents in vitro. However, their use as therapeutic agents, during a number of trials from the 1920s to the 1950s, was greatly handicapped by a number of factors. In part, there were certain limitations inherent in phage physiology (e. g. narrow host range, and rapid clearance from the body); in part there were technological limitations in the era (e.g. lysogeny not yet discovered); but the greatest limitation was the highly inadequate scientific methodologies used by practitioners at the time (e.g., their failure to conduct placebo-controlled studies, to remove endotoxins from the preparations, and to re-confirm phage viability after adding sterilizing agents to the preparations). In recent years, well-controlled animal models have demonstrated that phages can rescue animals from a variety of fatal infections, while non-controlled clinical reports published in Eastern Europe have shown that phages can be effective in treating drug-resistant infections in humans. This encouraging data, combined with the fact that drug-resistant bacteria have become a global crisis, have created a window of opportunity for phage therapy to be tested anew, this time using modem technologies and placebo-controlled designs. If successful, it can be used as a stand-alone therapy when bacteria are fully resistant to antibiotics, and as a valuable adjunct to antibiotics when the bacteria are still susceptible.