Health and Fitness Science

Bacteriophage: How A Forgotten Virus Can be An Asset to Combat Superbugs

What is the first word come to your mind after hearing the word ‘Virus’?

Disease, infection, infectious, harmful, etc. right.

What if tell you there are viruses that can cure our diseases.

Haven’t heard before! But there does exist such viruses, which are friendly to humans.

Just like there are god bacterias, there are good viruses.

These bacterias are known as ‘Bacteriophages’ or ‘Phages’meaning bacteria eaters.

These are good because ‘Bacteriophages’ are extreme enemies of deadly bacterias which has the potential to kill us. Believe it or not but phages are the most deadly beings on the planet.

Phages were discovered independently by two researchers Frederick William Twort at the University of London in 1915, and Félix d’Herelle who confirmed the finding and coined the term bacteriophage in 1917.

Below are some mind boggling facts about phages-

  • They are the most abundant microorganism on the planet. Much more in number than the total number of bacterias present. To give you an idea. They are everywhere, in soil, in water, in your body. Just your bare hand contains more than 10 billion phages. That’s a huge number right. The pie chart below depicts the number of phages compared to rest of the microorganism
Abundance of phages
  • Phages are 100 times smaller than bacterias. Under a normal microscope, they are not visible. You need an electrone microscope to see them.
  • The human gut contains almost one million billion phages. Whereas just one ml seawater contains one billion phages.

The most fascinating thing is that phages do not affect humans but only bacterias. Unlike other viruses phages can be a great weapon for us to fight with deadly bacterias.

How does a phage look like?

Bacteriophage Structure
Bacteriophage Structure

This is how a typical phage looks like. A head, a neck and a tail depicted in the above structure. Their genetic material is contained in a prism shaped head, surrounded by a protein capsid.

Like any other virus phages need a host cell in order to reproduce and become alive. When alone they are equivalent as dead.

Image of a phage under electron microscope
Image of a phage under electron microscope

How do phages kill deadly bacterias?

Phages are very specific in killing bacterias. What I mean is a particular type of phages can only kill a specific set of bacterias not all types of bacteria.

In order to kill a bacteria, phages first bind to the bind to specific receptors on the bacterial cell surface with their tail fibers and create a hole, a process which, along with attachment, is coordinated by the base plate.

Next,  a rigid tube is propelled out of the sheath, puncturing a hole in the bacterial cell membrane through which they inject their genetic material (DNA or RNA, double or single stranded).

From here, there are two ways via which phages can kill the host cell. One is known as lytic cycle, where after injecting (DNA or RNA) into the host cell, the phage genome synthesizes early proteins that break down the host DNA, allowing the phage to take control of the cellular machinery.

The phage then uses the host cell to synthesize the remaining proteins required to build new phages. During this process, the host cells gradually become weakened by phage enzymes (known as endolysin) and eventually burst. The whole process looks like the image below-

Different stages of lytic cycle
Different stages of lytic cycle

In another way, known as lysogenic cycle allows a phage to reproduce without killing its host. Following the injection of the phage DNA into the host cell, it integrates itself into the host genome, with the help of phage-encoded integrases, where it is then termed a prophage. The prophage genome is then replicated passively along with the host genome as the host cell divides. Something like shown in the below picture-

Different stages of lysogenic cycle

This process does not kill the bacteria directly but then under the right conditions (UV light, low nutrient conditions), the prophage can become active and come back out of the bacterial chromosome, triggering the remaining steps of the lytic cycle and kill the bacteria.

How does a phage decide whether to enter the lytic or lysogenic cycle when it infects a bacterium host cell?

One of the major factors is the number of phages infecting the host cell at once. Larger numbers of co-infecting phages make it more likely that the phages will use the lysogenic cycle.

This strategy may help prevent the phages from wiping out their bacterial hosts by toning down the attack if the phage-to-host ratio gets too high.

Because phages need a host cell to reproduce, they don’t want to run out of hosts. Thus, the tendency to flip to lysogeny at high abundance might have been favored by natural selection (explaining why phages are in such huge numbers).

But why are we suddenly interested in bacteriophages?

Although discovered first in 1917, we never paid enough attention to phages and there is a reason behind that.

In the earlier days, just a single cut in your body could have killed you. Bacterias were the culprits. We didn’t have any answer for them. People then moved their attention towards phages and successfully cured bacterial diseases by applying phages as weapons.

However, in 1928 Sir Alexander Fleming discovered penicillin and everything changed. We invented antibiotics and they were so effective against bacterias that we forgot about phages.

We became so habituated with antibiotics that we used them more and more for less and less serious causes. We lost respect for the little monsters (bacterias) and the weapon (antibiotics).

As a result, with time bacterias started to become immune against our invented weapon (antibiotics). Today there are hundreds of bacterias which are resistant towards most of our antibiotic. They are known as ‘multi drug resistant bacteria’.

Once we feared that soon there might be some bacterias that will be resistant to all our invented antibiotics and we will again go back in time, where a simple cut can kill us. Sir Alexander Fleming warned us-

there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.

We have already created such monsters known as ‘Superbugs‘. And believe it or not but they can wipe out human existence.

In fact, according to a survey, by 2050 superbugs could kill more humans a year than cancer. The days when a cut or cough or simple infection could kill you or your loved ones are coming back.

In such circumstances, scientists again turned their attention to forgotten tiny phages. In fact, phages are perhaps better than antibiotics to combat with bacterias.

Because antibiotics are like unguided missiles. It kills everything (good and bad bacteria) that comes within its range. But phages are very specific, they are like guided missiles.

By now, you already know how phages kill bacterias (discussed above).

In fact, there are many instances recently, where doctors have used phages to treat patients successfully.

You might be thinking, won’t bacterias develop ways of defending themselves?

They will evolve against phages too. But wait a minute, phages are also microorganisms, so they evolve too. There is a constant war going on between phages and bacterias from billions of years. Fortunately, phages won the battle almost all the time.

And even if bacterias become immune against phages someday, we will still be able to win against bacterias. It has been found that in order to become resistant to even just a few species of phages, bacteria have to give up their resistance to antibiotics. It’s like attacking the enemy with two different classes of weapons.

This has already been successfully tested patients who had no other hope left. Bacteria have no answer to the combination of phages and antibiotics.

But why don’t we hear more about phages in medical science?

Unfortunately, although there is a growing interest among scientists about phages but treatment via phages is still in an experimental state. Pharma companies are reluctant to invest in phages to a great extent. As a result, it has not become part of medical treatment. There is no official approval yet.

But things are changing, in recent years phages are getting more and more attention. Research is going on to see how safe phages are if we inject them from outside.

We better do more sound research on phages and make them a part of our medical treatment before superbug kills millions of lives all over the globe.

It might sound weird but injecting the deadliest being on the planet into the human body might save millions of lives. And who knows one day your doctor might write you a prescription for phages along with or instead of antibiotics.

An informative video on this topic-

Please, never use antibiotics mindlessly. Do remember what Sir Alexander Fleming said-

Sir Alexander Fleming On Antibiotic Resistence


  1. Technology networks
  2. Khan Academy-bacteriophage
  3. Phage treatment of human infections
  4. Encyclopedia Britannica
  5. Advantages and Limitations of Bacteriophage

Science Uncategorized

Superbugs: A Threat Of Global Annihilation

Imagine a world where a simple cut in the hand results in the death of a person. Sounds very unrealistic and fictitious right! 

However, our own world was like that once. Before Alexander Flemming discovered Penicillin, people used to die from a simple paper-cut, knee injury, throat problem anything which can lead to an infection. Simple because we didn’t have any arsenal which could fight with bacterias. 

Then the revolution happened in 1928 with the discovery of Penicillin by Alexander Flemming and a new era of medicine started. We got the weapons which can fight with bacterias and defeat them. But just within ten years, the same penicillin is no longer effective for the bacterias it used to kill earlier. By that time Bacterias had build their defense mechanism against penicillin. They knew how to tackle penicillin. And the fight between antibiotics and bacterias is going on to become better and better.

Let’s understand the fight with little details.                                                                                     So, what are antibiotics? 

Antibiotics are medicines that treat infections by inhibiting the growth of bacteria and killing them (Antibiotics works only on Bacteria, not on Viruses). Penicillin discovered by Alexander Fleming was the first kind of antibiotics used in the 1940’s and saved millions of lives.                                                                                                                                                 But how do antibiotics kill bacterias?

 Well, there are different mechanisms of action for different antibiotics. Some of them prevent bacterias from building their cell walls (which human cells don’t have), which is essential for their survival. Some antibiotics dissolve the membrane of the bacterial cell and some affect the protein building or DNA- copying mechanism of bacteria.

However, when you take an antibiotic to kill some bacteria, it not only kills the bad bacteria but also the friendly bacterias living in your body. So, you are also killing your own army during the killing of the opponent army. Thus a long-term dosage of antibiotics can kill enough of your friendly bacterias to make you sick.

That’s understood, but then how bacterias become better with time and develop a defense mechanism against drugs?

Bacterias have some special features. They can copy themselves very fast. Just within 24 hours, they can make billions of copies of itself. More importantly, they can exchange their DNA with each other effectively. They are always evolving new ways to fight off the antibiotics and becoming a better version of itself.  When we take an antibiotic for killing a particular bacteria, if all the bacterias are getting killed then that’s great, job done. But if somehow, even one bacteria survive that antibiotic attack, it will eventually develop a stronger defense mechanism against that antibiotic. 


Most dangerous fact is, then that one bacteria able to survive antibiotic attack will swap or exchange it’s DNA with other bacterias to make them also antibiotic resistant. On top of that, these bacterias will then make a huge army (which obviously will be antibiotic resistant) by copying themselves in just few hours.

Just imagine how dangerous is that! Thus it’s important to kill all the bacterias once you are taking an antibiotic.

You might think, so what if bacterias are becoming antibiotic resistance, what does that mean?

That means the end of the antibiotic era, which means we have no external weapons to use once any nasty bacteria attacks us to make us sick, very sick. Which also means you can literally die from any bacterial infection. Whether that infection is from a small cut or some other way.

The saddest part is we, ourselves helping those bacterias to develop antibiotic resistance. In India, over 58,000 babies died in one year as a result of infection with resistant bacteria usually passed on from their mothers. Globally the number of deaths due to antibiotic resistance is continuously increasing. Thinking how?

Are you one of those people who take medicine (antibiotics) in any occasions, for little headache, small injury or anything not very serious. Then be aware! you are giving your opponent bacterias way more chance to develop resistance. The more you expose them to drugs, the more quickly they will develop defense-mechanism. It’s like letting your enemy about your secret weapons. If you are using antibiotics frequently, bacterias will know about the secrets of your antibiotic and then that will be no longer effective against bacterias. So, use antibiotics wisely, keep it for situations when you have to use an antibiotic. Remember antibiotics are not effective against viruses. So there is no point of taking them for flu or cold. 

This one is very common I bet. I am sure you have seen others or done it yourself.              When Doctor prescribed you an antibiotic, they recommend us to finish the dosage of antibiotic. Most often what people do is, once they feel little better they stop taking the antibiotics further.                                                                                                                         Why do Doctors recommends to finish the full dosage even if you feel better?

Remember it’s very important to kill all the bad bacteria once you start taking antibiotics. When you start taking it, it will first kill the weaker ones (that’s why you feel better) but slightly more resistant ones are still there. If you complete your dosage all the bacterias will be killed but if you don’t, slightly resistant ones will be able to survive and then you know it can build a huge army which will develop resistance against that antibiotic. So listen to your doctor.

The most modern way that humans are accelerating antimicrobial resistance is the use of antibiotics in farm animals. Farms are anyway a great place for bacterias to grow. More than half of the antibiotics today are used for fast growth of farm animals like cattle, pigs even chickens. A low dosage of antibiotics are applied over a long period of time for quick growth of these animals. As a result, bacterias inside them easily develop antibiotic resistance. When we eat the meat of those farm animals, bacterias come in our body which are already resistant against antibiotics that we used to control them. Thus these poultry farms are a big threat to our health today. I would suggest rather to reduce your meat consumption from those farm animals.

Believe it or not but hospitals sometimes encourage the growth of antibiotic-resistant bacterias. Thinking how?

Hospitals often give patients broad-spectrum antibiotics means an antibiotic which can kill a broad range of bacterias. You are thinking what’s wrong with that?

Yes, chances of patients getting better in quick time are more with broad-spectrum antibiotics. However, because these antibiotics are not meant to kill a particular germ, they usually able to kill only weaker bacterias but not all the bacterias. Thus helps bacterias to build resistance against drugs. More dangerously, hospitals give patients this broad-spectrum antibiotic even when a more targeted drug that only kills the specific bacterium causing the illness would be enough.

Your personal hygiene also plays a crucial role in order to prevent these drug-resistant bacterias. Whether you are in a restaurant or hospital, don’t overlook hygiene.

As drugs are getting better so are bacterias. It’s a continuous fight which will go on.           The only thing we don’t want ever is to lose against them. For that to happen we need to use our drugs at the right moment so that we can surprise them and defeat them. If we continue using drugs for even small reasons rather they will surprise us by killing us even for small infections.

By the way, what is a superbug then?

A superbug is a microorganism that’s resistant to commonly used antibiotics. There are a number of superbugs known today. And if a bug is resistant to every available antibiotic, it would be the superbug of all superbugs which we never want to happen. In case that happens due to our negligence, then it will be the end of humankind. The annihilation of us. 

Sorry for these scary words but be aware and make others aware of this.                               I am very optimistic. And I am sure we shall overcome this threat and defeat those obnoxious Bacteria.

Alexander Fleming warned us long back by saying-

” …there is the danger that the ignorant man may easily underdose himself and by exposing his microbes to non-lethal quantities of the drug make them resistant.”
Alexander Fleming

 Don’t be that ignorant man or woman.


Have a fruitful week. Until next time.                                                                                                                                                                  – Joy





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