Bacteriophages, often referred to as “good viruses,” are viruses that specifically infect and destroy bacteria.
- Structure: They consist of a nucleic acid (either DNA or RNA, which can be single- or double-stranded) encased within a protein shell.
- Ubiquity: They are found extensively in nature, including in soil, water, and the human microbiome.
Key Characteristics:
- High Specificity: A crucial feature is their high specificity; they infect only select bacterial strains. This is a significant advantage over broad-spectrum antibiotics as it helps preserve beneficial microbiota.
- Self-Limiting Action: Bacteriophages multiply only when their target bacteria are present. Once the bacterial infection is cleared, the phages degrade, reducing the risk of overdose.
- Evolutionary Adaptability: They possess the ability to co-evolve with bacteria, enabling them to overcome bacterial resistance—a dynamic trait that is typically absent in conventional drugs.
Therapeutic Strategies:
- Natural Phage Therapy: This involves isolating the infecting bacteria from a patient, testing them against a library of different phages, and then culturing and administering the effective phage to the patient. Phages for this purpose are obtained from domestic or international phage banks.
- Genetically Engineered Phages: These are phages modified in laboratories to expand their host range, increase their effectiveness, or target dormant bacteria. They can be engineered to carry enzymes that break down bacterial biofilms or to bypass bacterial defense mechanisms.
Uses:
Bacteriophages are used in treating a variety of infections, including:
- Burns and diabetic foot ulcers
- Urinary tract infections
- Respiratory tract and gastrointestinal infections
- Multi-drug resistant (MDR) bacterial infections where antibiotics have failed.
Limitations:
A primary limitation of phage therapy is that each phage is specific to a particular bacterial strain. Therefore, effective treatment requires careful matching and personalization, meaning the correct phage must be identified for the specific bacterial infection.