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Bacterial Viruses as Antibiotics
The enemy of my enemy is my friend - Can bacterial viruses be used as antibiotics?

Viruses, often guilty of causing diseases in animals and plants, usually have the reputation of being the bad guys. But that is not true for all the viruses, it seems: some of them can actually be friends. A group of viruses which are capable of destroying bacteria, can be used for battling bacterial infections. These are termed bacteriophages, literally meaning “to-eat-bacteria”.

An article in the journal Biomacromolecules, April 2013, reports that, bacteriophages attached onto clinical surfaces, can be used to successfully eliminate biofilm formation by pathogenic bacteria, thus offering an effective means of controlling hospital-related infections. The researchers covalently attached two bacteriophages, coliphage T1 and staphylococcal bacteriophage Φ11, to polyethylene (PE) and polytetrafluoroethylene (PTFE) surfaces, and evaluated their effectiveness of combating two bacterial pathogens, E. coli and Staphylococcus aureus. The results revealed that the attached phages successfully retained their biological activity of infecting and destructing bacteria. Furthermore, it suggested that the two phages, attached simultaneously, have the ability of controlling multibacterial colonies.

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The idea of using bacteriophages as antimicrobial agents goes back a long way. According to literature, phages were used as therapeutic agents for treating bacterial infections since 1920s, following their discovery in 1917. Soon after the introduction of antibiotics in the 1940s, phage therapy was abandoned. However, antibiotics, once thought to be the brilliant solution against bacterial infections, have now proved otherwise. Despite the wide array of antimicrobial compounds introduced over the years, bacteria are increasingly becoming resistant to the antibiotics. Owing to the multidrug resistance of most pathogenic bacteria, the focus is back on bacteriophages as antibacterial agents. It is hoped that phage therapy could be used for successfully treating and preventing diseases caused by antibiotic resistant bacteria.

Bacteriophages are believed to possess many advantages over chemical antibiotics.

1. During an attack, phages, unlike antibiotics, can proliferate where it is needed, thus instinctively increasing the dose of the agent, while the antibiotic molecules are metabolically destroyed during the treatment. Therefore in contrast to the chemical antibiotics, a single dose or less frequent doses of phages can be effective in treatment.

2. Phages, being capable of undergoing genetic alterations, can overcome bacterial mutations. But antibiotics are chemicals that cannot adapt to a bacterial mutation and therefore become ineffective as the bacteria develop resistance traits.

3. Bacteriophages selectively target the pathogenic species of bacteria, while many broad spectrum antibiotics destroy the normal flora that can be beneficial in preventing the invasion by pathogens.

4. Phages have demonstrated an ability to clear bacterial biofilms which are resistant to chemical antibiotics. This may be attributed to the potential ability of the phages to actively penetrate into biofilms by lysing the bacterial layer, or due to the secretion of depolymerases that degrade the biofilm exopolymer.

There are also some limitations to page therapy.

1. Bacteriophages have a relatively narrow host range. Although this trait is advantageous in a sense, it can also be a handicap in treating multibacterial infections.

2. Bacteriophages, being foreign proteins, tend to be rapidly cleared from the circulation of humans. And there is a potential of the human immune system, mistakenly identifying the page-therapeutic agent as a pathogen, producing anti-phage antibodies to neutralise the page. There is also some risk of triggering allergic reactions to the phage particles.

Researches are being carried out on the prospect of genetically engineering bacteriophages in order to overcome these drawbacks and enhance the biological activity and effectiveness of phage antimicrobials.

Currently, many companies are involved in the development of phage-bases products for various sectors. Such products are being used as additives to control contaminations in food and animal feed, for treating plant diseases, in rapid detection test kits etc. Although phage therapy has yielded successful results in animal models, their application in treating humans is still limited. There is hope that bacteriophages, used in combination with antibiotics, is a potentially successful strategy to battle the ever developing antibiotic resistance of bacteria.[/align]

Further Reading:
1. Carlton, R. M. (1999). Phage therapy: past history and future prospects. Archivum Immunologiae et Therapiae Experimentalis-English Edition, 47, 267-274.

2. Hermoso, J. A., García, J. L., & García, P. (2007). Taking aim on bacterial pathogens: from phage therapy to enzybiotics. Current opinion in microbiology, 10(5), 461-472.

3. Loc-Carrillo, C., & Abedon, S. T. (2011). Pros and cons of phage therapy. Bacteriophage, 1(2), 111-114.

4. Pearson, H. A., Sahukhal, G. S., Elasri, M. O., & Urban, M. W. (2013). Phage-Bacterium War on Polymeric Surfaces: Can Surface-Anchored Bacteriophages Eliminate Microbial Infections?. Biomacromolecules.
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Its kind a funny thing The enemy of my enemy is my friend, but now i realize the importance of this while getting old our body capacity to fight against viruses and bacteria becomes very low so we need these bacteria's to help us.
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(05-16-2013, 02:07 AM)TobyForbes Wrote: Its kind a funny thing The enemy of my enemy is my friend, but now i realize the importance of this while getting old our body capacity to fight against viruses and bacteria becomes very low so we need these bacteria's to help us.

Hello TobyForbes,
I appreciate your interest. Actually what you say is true, we do need the 'friendly bacteria' in our body to help us fight off those 'bad bacteria' who make us sick. But this post is actually about a type of virus that can 'eat' bacteria. So we can use those viruses to get rid of those 'bad' bacteria. Usually those viruses do not do any harm to us but to the bacteria.
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