Now, with the looming terror of antibiotic resistance, there is an urgent need to find alternative treatment options. One being seriously considered is the use of bacteriophages, or phages for short, which are viruses that specifically target bacteria. Before the mass production of ‘magic bullet’ antibiotics, occurring in the 1940s and 1950s, a variety of infections were treated this way by physicians. However, at the time there was little understanding in how they worked and the crude therapies of the time were performed inconsistently, leading to a wane in interest for them upon the discovery of antibiotics.
How do they work? Phages first attach to and puncture the bacterial membrane, injecting DNA into the host cell. The host cell’s DNA transcription is suppressed, and phage-specific proteins are synthesized instead. New phages are assembled, the host cell membrane is disrupted, and large numbers of new phages are released from the host bacterium, which then consequently dies.
Today, to treat an unknown infection, a broad-spectrum of antibiotics that kill many types of bacterium may be given, whereas phages, unlike antibiotics, kill just one species or strain. With more and more bacterium strains becoming resistant to last-resort antibiotics and excessive use on farm animals to speed growth and prevent illness, the need for phage therapies is becoming increasingly evident. This is illustrated by the fact that, in 2014, the US National Institute of Allergy and Infectious Diseases highlighted phage therapy as one of seven approaches to “achieving a coordinated and nimble approach to addressing antibacterial resistance threats”. Moreover, there is growing concern that wiping out the human body’s beneficial microbes, when attempting to kill disease-causing ones in antibiotic treatment, can create a niche in which antibiotic-resistant bacteria can thrive.
The reason phages are extremely specific is because they have evolved to inhabit and kill one strain of bacteria. However, they are relatively safe to use as mammalian and plant cells lack the receptors required for phage infection, so phages are harmless against them.
Due to the specificity of bacteriophages, treatments can be designed to specifically target pathogenic bacteria while not negatively affecting the normal microbiota. That said, the high level of specificity also creates potential problems, the main one being the requirement of highly specific diagnostic procedures. Another potential problem with phage therapy includes the development of immunity and limitations with the registration of phage therapy options.
The benefits mentioned mean that governments are starting to pay attention to phage therapy, but pharmaceutical companies remain reluctant, as with phage therapy being nearly a century old, it is difficult for firms to establish this treatment as intellectual property and therefore recoup its costs. Thus, we are yet to see the role phage therapy will play within global health care and the fight against antibiotic resistance.
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