What is a bacteriophage (bacterial virus)?

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From the Guidelines

Bacteriophages are viruses that specifically infect and kill bacteria, consisting of genetic material enclosed in a protein capsid, and have the potential to be used as therapeutic agents against bacterial infections, especially those caused by antibiotic-resistant bacteria. They work by injecting their genetic material into bacterial cells, hijacking the bacterial machinery to produce more phage particles, and ultimately causing the bacteria to rupture and release new phages, a process known as the lytic cycle 1. This specificity and mechanism of action make bacteriophages highly effective and targeted therapeutic agents, with the potential to reduce side effects compared to broad-spectrum antibiotics.

Key Characteristics of Bacteriophages

  • They are highly specific, typically infecting only certain bacterial species or strains, which reduces side effects compared to broad-spectrum antibiotics 1.
  • They are naturally abundant in the environment, found wherever bacteria exist, and play a crucial role in bacterial population control in ecosystems.
  • Phage therapy involves using these viruses to target specific bacterial pathogens while leaving beneficial bacteria and human cells unharmed.

Phage Therapy and Its Potential

  • Phage therapy has been used for decades in some countries, particularly in Eastern Europe, and is gaining renewed interest worldwide as an alternative approach to combat the growing problem of antibiotic resistance 1.
  • The use of bacteriophages as therapeutic agents requires a standardized protocol for clinical laboratory evaluation, including phage susceptibility testing and characterization of phage properties, such as plaque morphology and lysis curves 1.
  • Recent studies have proposed pipelines for clinical phage microbiology, including the use of checkerboard interaction tests and survival assays to evaluate the efficacy of phage combinations and their potential interactions with antibiotics 1.

From the Research

Definition of Bacteriophage

  • A bacteriophage, also known as a phage, is a virus that infects bacteria 2, 3, 4, 5, 6
  • Bacteriophages are highly specific for their bacterial targets, meaning they only infect specific types of bacteria 3, 5

Characteristics of Bacteriophages

  • Bacteriophages have two different replication options: the lytic and lysogenic life cycles 6
  • In a lytic infection, the newly formed phage particles lyse the bacterium and continue to infect other bacteria 3
  • Bacteriophages can be applied topically or delivered by inhalation, orally, or parenterally 3
  • Phages are the only therapeutic agent that regulates itself at the sites of infection and decays when the infectious bacteria have been killed 5

Potential Applications of Bacteriophages

  • Bacteriophages are being explored as a potential treatment option for antibiotic-resistant bacteria 2, 3, 4, 5, 6
  • Phage therapy has shown promise in treating severe bacterial infections, including those caused by multidrug-resistant pathogens 2, 4
  • Bacteriophages can be used in combination with antibiotic agents, and the two often function synergistically 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Bacteriophage Therapy of Bacterial Infections: The Rediscovered Frontier.

Pharmaceuticals (Basel, Switzerland), 2021

Research

Phage therapy for severe bacterial infections: a narrative review.

The Medical journal of Australia, 2020

Research

Bacteriophages as potential treatment option for antibiotic resistant bacteria.

Advances in experimental medicine and biology, 2014

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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