Antibiotic - Definition, Types, Side Effects, Discovery, Do's & Don'ts

Antibiotic - Definition, Types, Side Effects, Discovery, Do's & Don'ts

Irshad AnwarUpdated on 20 Aug 2025, 06:24 PM IST

Antibiotics are medications used to combat bacterial infections. They work by targeting specific processes within bacterial cells, either inhibiting their growth or killing them directly. These medicines are crucial in treating illnesses like pneumonia, tuberculosis, and urinary tract infections. In the chapter Microbes in Human Welfare, students learn how different antibiotics play a major role in treating infections and improving overall health outcomes.

This Story also Contains

  1. Antibiotics Definition
  2. Antibiotics Names
  3. History Of Antibiotic
  4. Discovery Of Antibiotic
  5. Antibiotics Classification
  6. Antibiotics Drugs Name
  7. Effectiveness Of Penicillin
  8. Types Of Antibiotics
  9. Production Of Antibiotic
  10. Mode Of Action
  11. Uses Of Antibiotics
  12. Antibiotics Side Effects
  13. Tips, Tricks, and Strategies to Prepare for Antibiotics
  14. Weightage of Antibiotics in Different Entrance Exams
  15. Types of Questions Asked on the Topic Antibiotics in Different Exams
  16. MCQs on Antibiotics
  17. Frequently Asked Questions (FAQs)
Antibiotic - Definition, Types, Side Effects, Discovery, Do's & Don'ts
Antibiotics

The production of antibiotics often involves fermentation using microorganisms such as fungi and bacteria. These microbes are cultivated in controlled environments to ensure maximum yield of the active compound. Antibiotics not only save lives but also reduce the spread of diseases by eliminating harmful pathogens. They are one of the most effective tools in disease management and highlight the importance of biotechnology in medicine and human health advancements.

What Are Antibiotics

Antibiotics are drugs specifically tailored for combating bacterial infections in humans and animals. It works by either killing these bacteria or blocking their multiplication, hence in high demand through modern medicine. When asking what antibiotics are, it's important to recognize that they come in various forms, including pills, injections, and topical applications.

  • The proper understanding of antibiotics' names and their class is very vital for the treatment process to be effective.

  • Understanding what antibiotics are is crucial for effective treatment, as they do not work against viral infections like the flu or common cold.

  • It is essential to know about antibiotics and to use them responsibly to prevent antibiotic resistance, which can make future infections harder to treat.

Antibiotics Definition

  • Definition of Antibiotics refers to chemicals that can kill or stop bacteria development and are a crucial part of medical treatment.

  • Several varieties of drugs employed for humans and animals by antibiotics definition are meant to fight bacterial infections.

  • Understanding the antibiotics definition is important to recognize if such an antibiotic is effective against a certain pathogen but is ineffective against viruses.

  • In the context of the health sector, the antibiotics definition underscores the need for prudent use to avert the development of resistance.

  • The antibiotics are also defined according to their mechanism of action and spectrum of activity.

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Antibiotics Names

Antibiotics examples include a wide range of medications that are used to treat bacterial infections effectively. Antibiotics are crucial medications used to treat bacterial infections and some parasitic diseases. They function by either killing bacteria or inhibiting their growth, making them essential in modern medicine. Below is a table listing various antibiotics names along with their classifications and common uses.

Antibiotic Name

Class

Common Uses

Amoxicillin

Penicillin

Treats respiratory infections, ear infections

Ciprofloxacin

Fluoroquinolone

Treats urinary tract infections, bacterial diarrhoea

Doxycycline

Tetracycline

Treats acne, respiratory infections, Lyme disease

Azithromycin

Macrolide

Treats respiratory infections, STIs

Cefalexin

Cephalosporin

Treats skin infections, UTIs

Metronidazole

Nitroimidazole

Treats anaerobic bacterial infections

Gentamicin

Aminoglycoside

Treats severe bacterial infections

Clindamycin

Lincosamide

Treats skin and soft tissue infections

Sulfamethoxazole/Trimethoprim

Sulfonamide

Treats UTIs, respiratory infections

Vancomycin

Glycopeptide

Treats serious Gram-positive infections

These antibiotics names represent a variety of classes and are used to combat different types of bacterial infections effectively. Proper use of antibiotics is vital to minimize resistance and ensure their continued efficacy in treating infections. Understanding what are antibiotics can help patients make informed decisions about their health and recognize the importance of completing prescribed treatments.

History Of Antibiotic

In 1910 the first antibiotic, salvarsan was developed by scientist Paul Ehrlich. Salvarsan antibiotics are made up of arsenic compounds. This antibiotic is used as a remedy for syphilis disease. But in 1928 a true antibiotic was discovered by Alexander Fleming, named penicillin.

Discovery Of Antibiotic

Alexander Fleming discovered this antibiotic accidentally, when he was doing their work he found mold preventing growth of staphylococcus aureus by producing such type of chemical compound; after that he studied and identified the chemical compound and he discovered a novel penicillin antibiotic. So, he formed this penicillin with the help of bacteria and fungi.

Selman Abraham Waksman is the father of antibiotics and he discovered 20 natural antibiotics including streptomycin. Streptomycin is effective against tuberculosis disease.

Antibiotics Classification

Antibiotics are classified based on their mechanism of action, spectrum of activity, and chemical structure. Understanding the antibiotics classification of antibiotics is essential for selecting the appropriate treatment for bacterial infections. Below is a table that outlines various antibiotics classifications, and examples.

Antibiotic Class

Examples

Mechanism of Action

Penicillins

Amoxicillin, Penicillin G

Inhibit cell wall synthesis

Cephalosporins

Cefalexin, Ceftriaxone

Inhibit cell wall synthesis

Macrolides

Azithromycin, Erythromycin

Inhibit protein synthesis

Tetracyclines

Doxycycline, Tetracycline

Inhibit protein synthesis

Fluoroquinolones

Ciprofloxacin, Levofloxacin

Inhibit DNA replication

Aminoglycosides

Gentamicin, Tobramycin

Inhibit protein synthesis

Glycopeptides

Vancomycin

Inhibit cell wall synthesis

Lincosamides

Clindamycin

Inhibit protein synthesis

Sulfonamides

Sulfamethoxazole

Inhibit folic acid synthesis

Carbapenems

Meropenem, Imipenem

Inhibit cell wall synthesis

These antibiotics names represent a diverse range of classes that target bacteria in different ways. Proper classification of antibiotics is crucial for effective treatment and minimizing resistance. Understanding antibiotics names and antibiotics classification helps healthcare professionals make informed decisions in treating infections.

Antibiotics Drugs Name

Antibiotics are a class of drugs used to treat infections caused by bacteria. Some common antibiotics include amoxicillin, ciprofloxacin, and azithromycin, each serving specific medical purposes based on the type of infection. Understanding the names of these antibiotics is crucial for effective treatment and management of bacterial diseases.

Generic Name

Brand Name Examples

Common Uses

Amoxicillin

Amoxil, Augmentin

Treats respiratory infections, ear infections, and urinary tract infections.

Ciprofloxacin

Cipro

Used for urinary tract infections and certain gastrointestinal infections.

Azithromycin

Zithromax

Effective against respiratory tract infections and some sexually transmitted diseases.

Doxycycline

Vibramycin

Commonly used for acne and respiratory infections.

Clindamycin

Cleocin

Treats serious skin infections and some types of pneumonia.


Effectiveness Of Penicillin

Generally penicillin is used for the treatment of infection caused by the pathogenic bacteria. Each type of antibiotic is used for specific infection treatment. It works by two ways, first - it can kill the bacteria and second - by preventing the growth of bacteria.

Types Of Antibiotics

Antibiotics are categorized into several types, each with unique mechanisms of action and use. Understanding the different types of antibiotics is essential for effective treatment of bacterial infections.

Type of Antibiotic

Examples

Common Uses

Penicillins

Amoxicillin, Penicillin

Treats a variety of infections like strep throat and skin infections.

Cephalosporins

Cefalexin, Ceftriaxone

Used for respiratory infections and urinary tract infections.

Tetracyclines

Doxycycline, Minocycline

Commonly treats acne and respiratory infections.

Macrolides

Azithromycin, Erythromycin

Effective against respiratory and skin infections.

Fluoroquinolones

Ciprofloxacin, Levofloxacin

Used for serious bacterial infections, including UTIs.


Production Of Antibiotic

Generally, antibiotics are produced by the fermentation process by using bacteria or fungi, and can be synthesized by using chemicals. Antibiotics are produced by the batch fermentation process. Bacteria produce antibiotics as secondary metabolites during their growth.

Steps of production:-

  1. Production of antibiotics by the fermentation process, and

  2. Chemically synthesis of antibiotics.

A. Production of antibiotics by fermentation process

Following are the general steps for the production of antibiotics by the fermentation process.

1. Culture isolation

Isolation of starter culture according to antibiotic production is required. Culture transferred into nutritive media.

2. Fermentation process

Transfer of fermenting material within the batch fermentor and incubation with controlled environment such as temperature, pH, aeration and agitation, and availability of nutrition.

3. Isolation and Purification

It can be done by the use of water, oil, and organic solvents. For example, pentyl acetate (is an organic solvent) used in the purification of erythromycin antibiotic purification.

4. Packaging

Antibiotics can be packed in the form of a capsule, or tablet and filled within the vials.

B. Chemically synthesis of antibiotics

In the process of chemical production of antibiotics, the only difference is instead of nutritive median and starter culture we use chemicals.

Mode Of Action

Antibiotic affects bacteria in the following ways such as,

1. Inhibition of cell wall synthesis

2. Change in cell membrane potential

3. Inhibits protein synthesis process

4. Inhibits nucleic acid synthesis

5. Inhibits metabolic pathway of bacteria

Uses Of Antibiotics

Antibiotics are crucial medications used to treat various bacterial infections, effectively killing or inhibiting the growth of harmful bacteria. The uses of antibiotics include treating conditions such as pneumonia, urinary tract infections, and skin infections. Understanding the specific uses of antibiotics helps healthcare professionals select the appropriate treatment for their patients.

Antibiotic Class

Examples

Common Uses

Penicillins

Amoxicillin, Penicillin

Treats streptococcal infections, pneumonia, and skin infections.

Cephalosporins

Ceftriaxone, Cephalexin

Used for respiratory tract infections and meningitis.

Tetracyclines

Doxycycline, Tetracycline

Effective against acne, respiratory infections, and STDs.

Macrolides

Azithromycin, Erythromycin

Treats respiratory tract infections and certain STDs.

Fluoroquinolones

Ciprofloxacin, Levofloxacin

Used for UTIs, bronchitis, and severe bacterial infections.

Types of antibiotics encompass a wide range of medications that target different bacteria based on their mechanisms of action. Each type is designed for specific bacterial infections, making it essential to choose the right antibiotic for effective treatment.

Antibiotics Side Effects

Antibiotics can cause a variety of side effects, ranging from mild to severe. Common side effects include nausea, diarrhoea, and allergic reactions such as rashes or more serious conditions like anaphylaxis. Understanding the potential side effects of antibiotics is essential for safe and effective treatment.

Common Side Effects

Description

Nausea

Feeling sick or queasy, often leading to vomiting.

Diarrhea

Loose or watery stools, sometimes accompanied by cramps.

Allergic Reactions

Skin rashes, itching, or severe reactions like anaphylaxis.

Yeast Infections

Overgrowth of yeast in the mouth or vagina following antibiotic use.

Clostridium difficile Infection

A serious condition causing severe diarrhoea and abdominal pain.

Tips, Tricks, and Strategies to Prepare for Antibiotics

To effectively study the topic of Antibiotics: Types, Side Effects, Do's & Don'ts, consider these strategies:

Tips and Tricks
Mnemonic
Understand the classifications of antibiotics and their mechanisms.
CLASS (Classify, Learn Antibiotic Structures and Side effects)
Use flashcards to memorize the types and examples of antibiotics.
FLASH (Flashcards Lead to Active Study Habits)
Create a summary chart of side effects and dos & don'ts.
CHART (Concise Help for Antibiotic Review and Testing)
Practice MCQs to reinforce knowledge and application.
PRACTICE (Practice Regularly And Create Testing Insights for Excellence)

Weightage of Antibiotics in Different Entrance Exams

Knowing the weightage of this topic helps prioritize your study efforts. Here’s how it is weighted across various entrance exams:

Entrance Exam
Weightage (%)
5-10%
3-5%
4-6%
6-8%
2-4%

Types of Questions Asked on the Topic Antibiotics in Different Exams

Familiarizing yourself with the types of questions can help you prepare more effectively. Here’s a summary of the types of questions that may be asked across various exams:

Entrance Exam
Types of Questions
NEET
Conceptual questions, case studies
JEE Main
Multiple-choice questions on mechanisms
JEE Advanced
Analytical problems, application-based queries
AIIMS
Short answer questions, scenarios
UPSC
Descriptive questions on antibiotic usage and resistance

By utilizing these tips and understanding the exam weightage and question types, you can enhance your preparation for the topic of Antibiotics.

MCQs on Antibiotics

Q1. Antibiotics are mostly obtained from?

  1. Bacteria

  2. Viruses

  3. Angiosperms

  4. Fungi

Correct answer: 1) Bacteria

Explanation:

Antibodies are not primarily produced by bacteria but rather by specialized white blood cells called B lymphocytes or B cells, which can recognize antigens, which include bacteria and viruses. When an antigen enters the body, B cells recognize it, proliferate, and then differentiate into plasma cells that secrete antibodies specific to that antigen. Although some antibodies can be created in bacterial systems in laboratories for therapeutic use, in nature, the source is the immune system of animals; more so, in this case, humans.

Hence, the correct answer is option 1) Bacteria.

Q2. Which of the following statements regarding antibiotics is not correct?

(i) Antibiotics are attenuated microorganisms which in small concentrations can kill or retard the growth of other harmful microorganisms

(ii) Penicillin was the first antibiotic discovered by Alexander Fleming (1928) while working on bacterium Staphylococcus aureus

(iii) The full potential of penicillin as an effective antibiotic was established by Ernest Chain and Howard Florey

(iv) Fleming, Chain and Florey were awarded the Nobel Prize in 1945

  1. (i) only

  2. (iii) only

  3. (ii) and (iv)

  4. (ii), (iii) and (iv)

Correct answer: 1) (i) only

Explanation:

Microbes play a crucial role in various industries, synthesizing valuable products such as beverages, antibiotics, enzymes, organic acids, and biofuels. In the beverage industry, yeasts like Saccharomyces cerevisiae ferment sugars to produce alcoholic drinks like beer and wine, while lactic acid bacteria help in dairy product formation. Antibiotics such as penicillin (Penicillium notatum) and streptomycin (Streptomyces griseus) are derived from microbes to combat bacterial infections. Industrially important enzymes, like amylases from Bacillus subtilis, aid in food and detergent production, while Aspergillus niger produces citric acid for food preservation. Additionally, microbes contribute to biofuel production, with Saccharomyces species fermenting sugars into ethanol, making them essential for sustainable energy solutions.

Hence, the correct answer is option 1 (i) only.

Q3. Which one of the following population interactions is widely used in medical science for the production of antibiotics?

  1. Parasitism

  2. Mutualism

  3. Commensalism

  4. Amensalism

Correct answer: 4) Amensalism

Explanation:

Microbes in Industrial Products: Antibiotics -

Antibiotics are chemical substances, which are produced by some microbes and can kill or retard the growth of other (disease-causing) microbes. e.g., the antibiotic Penicillin. Antibiotics are chemicals secreted by one microbial group (eg: Penicillium) which harm other microbes (eg: Staphylococcus). It does not affect Penicillium or the organism which produces it.

Hence, the correct answer is option 4) Amensalism.

Also Read:

Frequently Asked Questions (FAQs)

Q1. What are antibiotics?
Antibiotics are chemical substances produced by microorganisms that kill or inhibit the growth of other harmful microorganisms, especially bacteria.

Q2. Who discovered antibiotics?
Antibiotics were discovered by Alexander Fleming in 1928 with the discovery of penicillin.

Q3. What are antibiotics based on mechanisms of action?
Antibiotics are based on mechanism of action, antibiotics are classified as cell wall synthesis inhibitors, protein synthesis inhibitors, nucleic acid synthesis inhibitors, and metabolic pathway inhibitors.

Q4. What are first generation antibiotics?
First-generation antibiotics are the earliest developed antibiotics that are effective mainly against gram-positive bacteria, such as first-generation cephalosporins.

Q5. What organisms do antibiotics target?
Antibiotics mainly target bacteria, and they are generally ineffective against viruses and fungi.

Frequently Asked Questions (FAQs)

Q: What is the meaning of antibiotics?
A:

The word antibiotics' name suggests ‘Anti’ means against and ‘Biotic’ means life.

Q: What is the effect of antibiotics on microbial cells?
A:

Antibiotics affect bateria by different ways, such as Inhibition of cell wall synthesis, Change in cell membrane potential, Inhibits protein synthesis process, Inhibits nucleic acid synthesis and Inhibits metabolic pathway of bacteria.

Q: Who is the father of antibiotics and why?
A:

Selman Abraham Waksman is the father of antibiotics, because he discovered 20 most important antibiotics including streptomycin and all antibiotics are synthesized by natural process.

Q: Who discovered a true antibiotic and gave their name?
A:

A true antibiotic was discovered by Alexander Fleming and it is named as penicillin.

Q: Which are the ways for synthesis of antibiotics?
A:

There are two ways of antibiotic synthesis; 1. Antibiotic production by  bacterial fermentation process and 2. Chemically synthesis of antibiotics.