Bacteria are single-celled microorganisms that can be seen only through a microscope. They are present almost everywhere as they play a vital role in our ecosystem. They are seen in large numbers in our surroundings like the air, soil, water, plants and even in our bodies.

Yes, our body contains different types of bacteria. It is estimated that our body contains more bacterial cells than human cells.

Good bacteria

Whenever we hear the name bacteria, we only think that they cause infections and are deadly. But did you know there are some good bacteria as well?

There are many bacteria that help our body in maintaining normal function and the activities we do on daily basis, such as digesting food. These bacteria are generally called "good bacteria" or "probiotics".

Some good bacteria are naturally present in our body, while others have to be included in our diet.

Most of the probiotics belong to Bifidobacterium and Lactobacillus species. These probiotics live in our gut and help in digestion.

Bifidobacterium makes up most of the "good" bacteria. They are present in our body naturally and start to multiply and form colonies in our gut as soon as we are born. Lactobacillus, on the other hand, does not occur naturally in our bodies. These bacteria need to be included in the diet. Lactobacillus acidophilus (in simple terms, lactic acid) is one of the bacteria that are responsible for fermenting milk into yoghurt, cheese and sour cream.    

Bad bacteria

While some bacteria are helpful to us, there are other bacteria that are pathogenic (disease-causing). Some of these bacteria cause mild infections in our body, while others can cause infections that are fatal.  

Do all the bad bacteria live inside our body?

There are a few bad bacteria that live in our body, but in normal circumstances, they do not harm our body. H. pylori are one among them. H. pylori are naturally present in and on the lining of our stomach. While they do not cause harm to everyone, they may be the reason for stomach ulcers in some people.  

Another bacterium that lives in our body is E. coli. E. coli is naturally found in our lower intestines. While some strains of these bacteria are helpful in digestion, others can be harmful. The harmful strains of E. coli are mainly associated with diarrhoea, urinary tract infections and pneumonia.

Most common bacterial infections

Typhoid is among the most common bacterial infections. It is caused by the Salmonella typhi bacteria. 

Strep throat is a bacterial infection that causes a sore and itchy throat.

Urinary tract infections include infection in any part of the urinary tract, including kidneys, ureters, bladder and urethra. Most infections are in the lower part of the urinary tract, which includes the bladder and urethra. It is more common in females than males.

Ear infections can be caused by both bacteria and viruses. Generally, the infection is seen in the middle ear. Many bacteria can cause ear infections, but the most common ones include Streptococcus pneumoniae and Haemophilus influenzae.

Whooping cough (pertussis) is a contagious respiratory infection caused by Bordetella pertussis bacteria.

Pneumonia is caused by a bacterial or viral infection in which the air sacs get infected, inflamed and gets filled with pus. 

Antibiotic therapy

Antibiotics are medicines that can kill or stop the growth of bacteria in our body. While antibiotics are very helpful in managing bacterial infections, they also kill the good bacteria in our gut.

Antibiotics are generally of two types: broad and narrow-spectrum antibiotics. As the name suggests, broad antibiotics are capable to kill or stop the growth of a large group of bacteria, while narrow-spectrum antibiotics work against a few specific species of bacteria. 

Generally, doctors prescribe broad-spectrum antibiotics initially. These antibiotics, being able to kill the majority or broad categories of bacteria can also kill the good bacteria in our gut. This is the reason why people on antibiotics feel stomach pain, loose motions, and loss of appetite.

So, can we do something about it?

Yes, we can. Whenever we are on antibiotics, we should make sure that we are also taking probiotics. This will help to balance the good bacteria in our gut.  

Also, many people take unnecessary antibiotics. During a common cold or flu, they think because it’s an infection, taking antibiotics will help. But that’s not true. Antibiotics help only when the infection is caused by bacteria and not a virus or fungi.

Generally, viral infections like the common cold subside on their own. We don't have to take any antiviral agents.