Introduction
Traditionally associated with Paul Ehrlich’s “magic bullet” and Alexander Fleming’s discovery of penicillin, the start of the “antibiotic era” sparked a cascade of research and innovation in medicine, saving millions of lives from one of the leading causes of human morbidity prior to the twentieth century: bacterial infections.[2] As soon as antibiotics were introduced to the public; however, many bacterial species became resistant to the drugs they were once sensitive to. This means novel therapies are required, such as the discovery of new, novel antibiotics or the use of bacteriophage (phage) therapy.
Bacteriophages are a class of viruses that exclusively infect bacteria. There are two types – lytic and lysogenic – that largely differ in whether they kill the host during their replication cycle (lytic) or integrate themselves into the host’s genome (lysogenic). In fact, a defining characteristic of bacteriophages is that they are host-specific and will only target bacteria that they can successfully infect. Phage therapy utilizes this principle by using targeted-lytic phages to kill antibiotic-resistant bacteria present in infections.[3] This paper will explore what bacteriophages are and how they can be utilized to treat antibiotic-resistant infections.
What is antibiotic resistance?
Antibiotic resistance is caused by the overuse and misuse of antibiotic treatments (Figure 1). Essentially, when bacteria are repeatedly exposed to antibiotics, selective pressures can emerge in which bacteria with antibiotic-resistance mutations and genes grow and proliferate in the environment.[4] These scenarios often occur when inappropriate antibiotics are prescribed or if patients fail to complete the recommended dosing regimens.[5, 6]