Bacteriophages, also known as phages, are viruses that infect and replicate specifically within bacteria and archaea. They are composed of proteins that encapsulate a DNA or RNA genome and can have simple or elaborate structures. Bacteriophages are among the most common and diverse entities in the biosphere, found wherever bacteria exist.
Phages work by binding to a susceptible bacterium and injecting its genetic material into the host cell. Once inside the bacterial cell, the phage hijacks the bacteria’s cellular machinery, preventing it from producing bacterial components and forcing it to produce viral components instead.
As new phages are assembled within the bacterial cell, they eventually cause the cell to rupture (lysis), releasing new phage particles that can infect other bacterial cells. This process of infection, replication and lysis is the main mode of action of bacteriophages in eliminating bacteria.
Differences between antibiotics and Bacteriophages
Bacteriophages and antibiotics are both used to combat bacterial infections, but they differ in several aspects:
Target specificity: Bacteriophages are viruses that specifically infect and replicate within bacterial cells, targeting specific species or strains of bacteria while leaving others unharmed.
Antibiotics, on the other hand, can have a broader spectrum of activity, affecting multiple bacterial species and sometimes even harming beneficial bacteria in the human microbiome.
Mode of action: Bacteriophages kill bacteria by infecting them and causing them to rupture (lyse) as new phages are produced inside the bacterial cell. Antibiotics act through several mechanisms, such as inhibition of cell wall synthesis, interruption of protein synthesis or interference with nucleic acid synthesis.
Development of resistance: Bacteria can develop antibiotic resistance through mechanisms such as antibiotic inactivation, target modification, altered permeability, and diversion. Although bacteria can also develop resistance to bacteriophages, modifications that promote phage resistance can increase their susceptibility to antibiotics, potentially working synergistically with antibiotics to enhance their effectiveness.
Self-replication: Unlike antibiotics, bacteriophages can multiply within the bacterial host, meaning fewer phage units are needed per treatment, and the concentration of phage can increase over time as they replicate.
Environmental impact: Bacteriophages have a smaller environmental impact compared to broad-spectrum antibiotics, as they are predominantly composed of nucleic acids and proteins and have relatively narrow host ranges, affecting only a small subset of environmental bacteria.
In summary, bacteriophages are more specific, have a different mode of action and may have a lower environmental impact compared to antibiotics. They also have the ability to self-replicate, potentially reducing the dosage required for treatment. However, both bacteriophages and antibiotics face the challenge of resistance developing in bacteria.