Phage therapy (PT) is also called bacteriophage therapy. It uses viruses to treat bacterial infections. Bacterial viruses are called phages or bacteriophages. They only attack bacteria; phages are harmless to people, animals, and plants.

Bacteriophages are the natural enemies of bacteria. The word bacteriophage means “bacteria eater.” They’re found in soil, sewage, water, and other places bacteria live. These viruses help keep bacteria growth in check in nature.

Phage therapy might sound new, but it has been used for 100 years. However, the treatment isn’t well known. More research is needed on bacteriophages. This therapy for disease-causing bacteria may be a useful alternative to antibiotics.

Bacteriophages kill bacteria by making them burst or lyse. This happens when the virus binds to the bacteria. A virus infects the bacteria by injecting its genes (DNA or RNA).

The phage virus copies itself (reproduces) inside the bacteria. This can make up to 1000 new viruses in each bacterium. Finally, the virus breaks open the bacteria, releasing the new bacteriophages.

Bacteriophages can only multiply and grow inside a bacterium. Once all the bacteria are lysed (dead), they’ll stop multiplying. Like other viruses, phages can lay dormant (in hibernation) until more bacteria show up.

Antibiotics are also called anti-bacterials. They’re the most common type of treatment for bacterial infections. Antibiotics are chemicals or drugs that destroy bacteria in your body.

Antibiotics save lives and prevent disease from spreading. However, they can cause two main problems:

1. Antibiotics attack more than one kind of bacteria

This means they can kill both bad and good bacteria in your body. Your body needs certain kinds of bacteria to help you digest food, make some nutrients, and keep you healthy.

Good bacteria also help stop other bacterial, viral, and fungal infections from growing in your body. This is why antibiotics can cause side effects like:

  • upset stomach
  • nausea and vomiting
  • cramping
  • bloating and gassiness
  • diarrhea
  • yeast infections

2. Antibiotics can lead to “superbugs”

This means that instead of stopping, some bacteria become resistant or immune to antibiotic treatment. Resistance happens when bacteria evolve or change to become stronger than the antibiotics.

They can even spread this “superpower” to other bacteria. This may trigger dangerous infections that cannot be treated. Untreatable bacteria can be deadly.

Use antibiotics correctly to help prevent resistant bacteria. For example:

  • Only use antibiotics for bacterial infections. Antibiotics will not treat viral infections like colds, flus, and bronchitis.
  • Don’t use antibiotics if you don’t need them.
  • Don’t pressure your doctor to prescribe antibiotics for you or your child.
  • Take all antibiotics exactly as prescribed.
  • Complete the full dosage of antibiotics, even if you feel better.
  • Don’t take expired antibiotics.
  • Throw away expired or unused antibiotics.

The benefits of phage therapy address the shortcomings of antibiotics.

Just as there are many kinds of bacteria, there are several types of bacteriophages. But each kind of phage will only attack a certain bacterium. It won’t infect other kinds of bacteria.

This means that a phage can be used to directly target disease-causing bacteria. For example, a strep bacteriophage will only kill bacteria that cause strep throat infections.

A 2011 research review listed some pros of bacteriophages:

  • Phages work against both treatable and antibiotic-resistant bacteria.
  • They may be used alone or with antibiotics and other drugs.
  • Phages multiply and increase in number by themselves during treatment (only one dose may be needed).
  • They only slightly disturb normal “good” bacteria in the body.
  • Phages are natural and easy to find.
  • They are not harmful (toxic) to the body.
  • They are not toxic to animals, plants, and the environment.

Bacteriophages are not yet widely used. This therapy needs more research to find out how well it works. It’s not known if phages may harm people or animals in ways unrelated to direct toxicity.

Additionally, it’s not known if phage therapy may trigger bacteria to become stronger than the bacteriophage, resulting in phage resistance.

Cons of phage therapy include the following:

  • Phages are currently difficult to prepare for use in people and animals.
  • It’s not known what dose or amount of phages should be used.
  • It’s not known how long phage therapy may take to work.
  • It may be difficult to find the exact phage needed to treat an infection.
  • Phages may trigger the immune system to overreact or cause an imbalance.
  • Some types of phages don’t work as well as other kinds to treat bacterial infections.
  • There may not be enough kinds of phages to treat all bacterial infections.
  • Some phages may cause bacteria to become resistant.

Phage therapy isn’t yet approved for people in the United States or in Europe. There has been experimental phage use in a few rare cases only.

One reason for this is because antibiotics are more easily available and are considered to be safer to use. There is ongoing research on the best way to use bacteriophages in people and animals. The safety of phage therapy also needs more research.

In the food industry

Phage therapy is being used in the food industry, however. The U.S. Food and Drug Administration (FDA) has approved of some phage mixtures to help stop bacteria from growing in foods. Phage therapy in food prevents bacteria that can cause food poisoning, such as:

The phages are added to some processed foods to help prevent bacterial growth.

Another use for phage therapy that is being tested involves adding bacteriophages to cleaning products to destroy bacteria on surfaces. This may be beneficial in hospitals, restaurants, and other places.

Phage therapy may be very important in treating infections that don’t respond to antibiotics. For example, it may be used against a powerful Staphylococcus(staph) bacterial infection called MRSA.

There have been successful cases of phage therapy use. One such success story involved a 68-year-old man in San Diego, California, who was treated for a resistant kind of bacteria called Acinetobacter baumannii.

After more than three months of trying antibiotics, his doctors were able to stop the infection with bacteriophages.

Phage therapy isn’t new, but its use in people and animals also isn’t well researched. Current studies and some successful cases may mean that it could become more common. As phage therapy is considered safe and approved for use in the food industry, this may be quite soon.

Phage therapy is nature’s “antibiotics” and may be a good alternative treatment. It may also be beneficial for other uses such as a surgical and hospital disinfectant. More research is needed before its use is approved for people.