Phage Therapy

Bacteriophage therapy is a method of treating bacterial infections, and a newly developing alternative to antibiotics. In several European countries, phage are being used regularly for this purpose. They are used to treat tropical infections, such as nasal abscesses. At times, they have been proven effective at preventing the amputation of infected limbs in people who have an antibiotic resistant infection. Despite their obvious advantage over antibiotics, their use has been limited by the Food and Drug Administration. The topic continues to be controversial

Phage therapy has several benefits over other methods of treating bacterial infections:

1. The observance of bacterial resistance to antibiotics is significantly higher to than resistance to phages. However, when mutant bacteria do gain immunity to phage particles, this can be overcome by treating the infection with a phage "cocktail", a careful mixture of different kinds of phages. The presence of a variety of phages (that target variety of surface receptors on bacterial cell walls) significantly reduces the survival chances of even mutant bacteria.
2. Bacteriophage have a very narrow host range, meaning they will not infect bacteria they are not targeted to infect. This specificity is an advantage when it comes to treating bacterial infections inside organisms. For example, our bodies contains symbiotic bacteria that are necessary for our survival. Since antibiotics can destroy a wide range of bacterial species, they can cause various side effects that are virtual absent in when using phage therapy.
   
3. Usage of phage therapy also eliminates other problems that come with the use of antibiotics, such as the misuse or overdose of medication. Since phage naturally multiply between lysis of bacterial cells, their repeated usage is usually unnecessary. In the case of antibiotics, repeated prescription is very important to continuously treat the infection, a characteristic that also significantly raise costs of treatment.
4. While it is often quite expensive and time consuming to create new antibiotics, as well as study its potential side effects, it is relatively inexpensive and quick to develop a phage therapy for a certain bacterial infection. Being the most abundant and diverse organisms on the planet, it is possible to isolate a novel phage from any given environmental sample. However, it is important to know the exact species of bacteria being treated, because, as mentioned before, phages have a very specific host range.
   

Further reading:
http://www.popsci.com/scitech/article/2009-03/next-phage
http://www.pharmas.co.uk/blog/bacteriophage-treatments