Antibiotic Definition

Edited By Irshad Anwar | Updated on Sep 30, 2024 07:10 PM IST

Antibiotics are drugs synthesized from other organisms (for example, moulds, fungi, and some soil bacteria) to help fight harmful microorganisms. However, they are not very useful against some microbes, including viruses. Antibiotics are made on a very large scale with the help of the fermentation process. A large tank is made available with the growth medium that secretes nutrition for the microorganism’s growth. Regulation of temperature, pH levels, oxygen levels, and nutrient parameters in the fermentation tank is the most important step in producing antibiotics. Antibiotics are one of the important topics in biology which comes under chapter microbes in human welfare class 12th. The topic carries weightage of 5 to 6% of total marks in NEET, Paramedical or Pharmacy entrance exams.

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This Story also Contains

Antibiotic Definition
History Of Antibiotic Production
Different Types Of Antibiotics
Mechanism Of Action Of Antibiotics
Side Effects Of Antibiotics
Tips, Tricks, And Strategies To Prepare For Antibiotics
Types Of Questions Asked On Antibiotics
Weightage Of Antibiotics In Different Entrance Exams
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Antibiotics are defined as the chemical compounds that are responsible for killing or stopping the growth of bacteria. Truly speaking, antibiotics are defined as a further class of organic anti-infective agents that are usually produced from bacteria or moulds that are toxic to many other bacteria and can kill them. However the term "antibiotic" is now used in an easy way to refer to anti-infectives produced from synthetic and semisynthetic compounds.

History Of Antibiotic Production

Going back to 1928, Scottish bacteriologist Alexander Fleming saw some colonies of bacteria that were growing on a culture plate, and these colonies had been affected by a mould species. Some more important events related to the antibiotic invention and its production are discussed below:

Another biochemist Ernst Chain, Australian Pathologist Howard Florey, and other scientists later on invented that isolated active ingredient that was responsible for killing the bacteria. They named it penicillium.
The penicillium species were formed on the contaminated bacterial culture and it killed the bacteria which were surrounding it.
Later on, penicillium was one of the most effective tools against some of the serious bacterial infections.
There are different types of penicillin available today to treat different bacterial infections.
By the 1950s there had been several chemical modifications made to the penicillin molecule which led to the formation of semisynthetic penicillin.

Different Types Of Antibiotics

There have been several modifications made to penicillin since it was developed. Several forms of antibiotics were formed to fight several diseases which are based on bacterial infections. Some of the major antibiotics and their backgrounds and treatments are discussed below:

Type	Key Features	Common Uses	Background
Penicillins	First discovered antibiotics; effective against many bacteria.	Sore throat, skin infections, respiratory issues.	Discovered by Alexander Fleming; works by disrupting bacterial cell walls.
Tetracyclines	Broad-spectrum; inhibits protein synthesis; photosensitive.	Acne, UTIs, STDs, eye infections.	Effective against a wide range of bacteria; not recommended for young children due to dental effects.
Cephalosporins	Similar to penicillins; effective against gram-negative bacteria.	Ear infections, UTIs, lung infections.	Used for patients allergic to penicillin; kills bacteria effectively.
Macrolides	Good for respiratory and skin infections; inhibits protein synthesis.	Pneumonia, whooping cough, skin infections.	Alternative for those allergic to penicillins; effective against community-acquired infections.
Sulfonamides	Works against both gram-positive and gram-negative bacteria; inhibits folic acid production.	UTIs, pneumonia, ear infections.	Can cause allergic reactions and kidney stones with long-term use.
Glycopeptides	Targets serious infections from gram-positive bacteria like MRSA.	MRSA infections, endocarditis, C. difficile.	Inhibits cell wall formation; Vancomycin is a key example; may cause red man syndrome with prolonged use.

Mechanism Of Action Of Antibiotics

The table mentioned below contains all the steps which are involved in the mechanism of antibiotics.

Process	Stages
Target recognition	The antibiotics enter the bacterial cell and recognise a specific target that can be either cell wall, ribosome, DNA or some kind of metabolic enzyme.
Binds to the Target	After recognising the target the antibiotic attaches itself to the target. These targets can be of different chemical formulations such as cell wall replication enzymes, folic acid synthesis enzymes and sometimes even the DNA.
Growth/inhibition or Death	In this stage, the antibiotic directly kills the bacteria. These are also known as Bactericidal Antibiotics.
	There are also antibiotics which are bacteriostatic which means they inhibit bacterial growth. Attack on the immune system to eliminate the bacteria. (e.g: tetracyclines)
Elimination of the bacteria	After the bacteria has been killed our immune system discards the dead bacteria. This helps in saving the immune system and body from severe bacterial disease.

Side Effects Of Antibiotics

Regular use of antibiotics can lead to certain side effects which can be serious. Antibiotics with their side effects are mentioned in the table below:

Type of antibiotic	Common side effects after long-term use
All Antibiotics	Diarrhea, nausea, vomiting and rashes
Tetracyclines	Photosensitivity ( redness in the sunlight)
Fluoroquinolone	Muscle and skeletal tissue pains. Lower Spine region pain.
Macrolides	Ear problems ( loss of hearing)
Penicillin	Low white blood cell count.
Sulfonamides	Kidney stones formation.

Tips, Tricks, And Strategies To Prepare For Antibiotics

It's hard to remember everything in a single go. We made the entire problem easy. Some of the tricks regarding antibiotics are given below which you can use to memorize the important points.

ANTIBIOTICS: Important Points

A: Antimicrobial
N: Not for Viruses
T: treatment for Bacterial Infections
I: inhibits the growth of Bacteria
B: works against Bacterial Resistance
O: oral / IV use
T: Test for Effectiveness
I: interactions
C: Common side effects are nausea, diarrhoea and allergic reactions.

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Classification of Antibiotics

P: Penicillin
C: cephalosporins
T: tetracycline
M: Macrolides
S: Sulfonamides

Side effects mnemonics

N: Nausea
D: Diarrhea
A: Allergic reactions
H: Hearing Loss
K: Kidney Stones

Types Of Questions Asked On Antibiotics

During the preparation of the exam, there are different types of questions asked about Antibiotics in different forms. The table given below contains the different patterns of questions asked in different exams.

Exam type	Types of questions asked
CBSE	Definition of Antibiotics and its types. Benefits. Uses of Antibiotics. Side effects of Antibiotics.
NEET	Mechanism of Action of Antibiotics. Use of Antibiotics in Treatments. Different types of antibiotics. Use of different types of antibiotics.
Paramedical	Medications based on antibiotics. Types of antibiotics. Side effects of antibiotics. Treatment of side effects of antibiotics.

Weightage Of Antibiotics In Different Entrance Exams

It is important to keep weightage of the topic in mind throughout the preparation. The weightage of antibiotics in different exams is mentioned below in the table: