Bookmark added to your notes.
View Notes


Every organism on this planet including human beings is susceptible to infections caused by bacteria. In older times, when advancements in the field of medicines were not much, even the small cuts, bruises or wounds would turn fatal. Common cold, diarrhea, etc. also had the potential to develop into serious illnesses. So, the discovery of antibiotics was a major breakthrough in the field of medicine. The first-ever discovered antibiotic was Penicillin.

What are Antibiotics?

An Antibiotic is an antimicrobial substance obtained from other organisms that helps to combat harmful and infectious bacteria. Technically, any drug that kills pathogens in the body is antibiotics. Except, they cannot combat viral infections as antibiotics cannot kill viruses.

Antibiotics are obtained by the fermentation process and they are produced on a large scale by health care industries. The fermentation, in this case, is chemical fermentation that is induced by the microorganisms in a large tank. A large tank is filled with a growth medium that provides nutrition for the growth of useful microbes. Various parameters that are maintained are an optimized temperature, organism-specific pH levels, and oxygen and nutrient supply to the fermentation tank. Once the production of the antibiotics is done, they are extracted from the medium and purified through multiple physical processes. The purified antibiotics are converted into a crystallized form.

How Do Antibiotics Work?

Antibiotics are also called antibacterial as they combat bacterial infection. They either kill the infection-causing bacteria or reduce their growth. Antibiotics are powerful medications for people even with certain severe infections. Not only do they cure serious infections but prevent less serious infections from becoming serious. Antibiotics combat the bacteria by following three ways-

  • By attacking the bacterial cell wall or coating that protects the bacteria.

  • By interfering with their reproduction in the body.

  • By blocking bacterial cells to produce proteins.

As soon as you start your antibiotics, they start their activities in the body. But you may still feel unwell for 2 to 3 days after taking them. The effectiveness of the antibiotic depends on the type and also the intensity of infection one suffers from. It takes more time to treat a serious infection. They are mostly taken for 7 to 14 days. However, the right dosage and schedule of a particular drug should only be prescribed by a practicing doctor. Even if you start feeling well after a few doses, you must continue the drug doses until the full prescribed schedule. This is because, as soon as antibiotics are taken, they start killing the bacteria, but mostly the weak ones are killed first and the stronger ones still remain in your system, which may cause you ill again if the drugs are stopped midway.

Antibiotic Resistance

When you take an antibiotic, the sensitive bacteria are eliminated first. The strong bacteria that survive the antibiotic treatment often become resistant to that particular antibiotic. These bacteria often have unique characteristics that prevent the action of antibiotics from working on them. Thus, antibiotic resistance occurs when bacteria can no longer be killed or controlled by certain antibiotics, which previously were useful.

Using the wrong antibiotic for infection may also lead to resistance. Therefore, antibiotics prescribed for someone else should be taken. Neither are the left-over antibiotics useful from a previous treatment. Only the doctor or health care practitioner will be able to select the most appropriate antibiotic for a specific type of infection.

Uses of Antibiotics

Since the discovery of antibiotics, mortality rates due to bacterial infections have reduced and lifespan has increased.

Microbial infections have the potency to wipe out an entire population of organisms. For example, anthrax is a disease that infects livestock and humans may even contract it, which can be fatal unless it is treated.

Antimicrobial therapy is used to destroy or to prevent microbial growth. However, it might not stop the infection from spreading. For example, the anthrax-causing bacterium Bacillus anthracis does not actually kill the host, instead, it is the toxins that are produced that prove to be fatal. So, antibiotics might kill the bacteria, but the toxins released by the bacteria remain in the body and continue to cause infection.

Two Types of Antimicrobial Therapies are in Use:

1.  Microbicidal therapy – Is used to kill microorganisms.

2.  Microbiostatic therapy – Is used to prevent the growth of microorganisms.

FAQ (Frequently Asked Questions)

1. Which is the First Discovered Antibiotic?

Penicillin was the first-ever “true” antibiotic, discovered by a Scottish bacteriologist, Alexander Fleming in 1929. It was used to treat various bacterial infections that plagued man in olden times. Ironically, Penicillin was accidentally discovered, but it was a landmark discovery in the field of medicine. Penicillin was obtained from a mold called Penicillium notatum.

The types of Penicillin, as per their effectiveness are as follows-

Penicillin VK – It is used to combat bacterial infections. 

Example: Ear infection.

Penicillin G – It is more effective against gram-positive and gram-negative cocci infections. 

Example: bacterial infections in the stomach.

2. What are the Classes of Antibiotics? Give Examples.

List of 10 Different Generic Classes of Antibiotics is Given Below-

Classes of Antibiotics (Types)



















sulfamethoxazole and trimethoprim

amoxicillin and clavulanate