Phage therapy
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Bacteriophages or "phage" are viruses that invade bacterial cells and, in the case of lytic phages, disrupt bacterial metabolism and cause the bacterium to lyse [destruct]. Phage Therapy is the therapeutic use of lytic bacteriophages to treat pathogenic bacterial infections. Phage therapy is an alternative to antibiotics, being developed for clinical use by many western research groups in Europe and the US. It has been extensively used and developed in the former Soviet Union.
The treatment is effective by using a phage virus to infect and kill specific bacteria whilst not interacting with the surrounding human tissue or other harmless bacteria. The virus replicates quickly so a single, small dose is usually sufficient.
Phages are currently being used therapeutically to treat bacterial infections that do not respond to conventional antibiotics.
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History of Phage therapy
In Russia from the time of Stalin there has been extensive research and development in this field. Isolated from Western advances in antibiotic production in the 1940s, Russian scientists continued to develop already successful phage therapy to treat the wounds of soldiers in field hospitals. The success rate was as good as, if not better than any antibiotic, and Russian researchers continued to develop and to refine their treatments and to publish their research and results.
For various reasons, not least the impermeability of the Russian language to Western researchers, Russian advances in the field remain relatively unknown in the West.
There is an extensive library and research centre at the Tbilisi Institute in Georgia. Phage therapy is today a widespread form of treatment in countries that were formerly members of the Soviet Union.
Collecting and testing Phage
In its simplest form, phage treatment works by collecting samples likely to contain viruses, for example effluent outlets and faeces and other sources. The samples are taken and applied to growth medium containing the bacteria that is wished to be combatted. The growth medium are then tested to see which one fails to grow. The phage are then amplified and distributed.
Benefits of Phage Therapy
The most apparent benefit of phage therapy is that bacteria cannot easily develop resistance to phages. The reason behind this is that phages replicate and undergo natural selection and have probably been infecting bacteria since the beginning of life on this planet. Although bacteria evolve at a fast rate, so too will phages. Bacteria are most likely to modify the molecule that the phage targets, which is usually a bacterial receptor. In response to this modification phages will evolve in such a way that counteracts this change, thus allowing them to continue targeting bacteria and causing cell lysis. As a consequence phage therapy is likely to be devoid of the problems similar to antibiotic resistance.
Bacteriophages are very specific, targeting only particular strain of bacteria. Traditional antibiotics have a wide-ranging effect, meaning that they kill both harmful and useful bacteria (such as those facilitating food digestion). The specificity of phage reduces the chance that useful bacteria are killed when fighting an infection.
The machinery and regulation pathways in eukaryotes are different from bacteria, therefore preventing eukaryotes acting as hosts.
Increasing evidence shows the ability of phages to travel to a required site, this can include the brain, where the blood brain barrier can be crossed and multiply in the presence of an appropriate bacterial host, combating problems such as meningitis.
Development and production is faster than antibiotics, on condition that the required recognition molecules are known.
Research groups in the West are seeking to develop broad spectrum phage and targeted MRSA treatments in a variety of forms - including impregnated dressings for wounds.
Application of Therapeutic Phages
Phages are "host specific" and it is therefore necessary in many cases to match phages to the patient's infection prior to treatment. Some bacteria, for example Clostridium and Mycobacterium, have no known therapeutic phages available - however isolation of therapeutic phages can typically require a few months to complete if there are sufficient host bacterial strains available for testing.
Phages can work if applied orally, topically on infected wounds or spread onto surfaces, and used during surgical procedures.
Where to Get Treatment
- Phage Therapy Center, Tbilisi, Republic of Georgia
- Herzfeld Institute, Polish Academy of Science
References
- Lindalee Tracey and Emmanuel Laurent, "Killer Cure", Films à Trois, 2005
- Pirisi A. Phage therapy: advantages over antibiotics? Lancet 2000; 356: 1418. PMID 11052592.
- Brussow H. (2005). Phage therapy: the Escherichia coli experience. Microbiology. 151:2133-40
- Intralytix
- Phage International Inc.