How Do Antibiotics Work? Mechanisms and Examples
Antibiotics can be defined as the substances that can be used to treat bacterial infections. Some antibiotics also act as antiprotozoal substances, which suggests they're effective against protozoan infections. However, no antibiotics are effective at combating viruses,; hence, to curb viral infections, antiviral drugs are used.
The origins of the term “antibiotics” are often traced back to the 1800s’ when French bacteriologist Jean Paul Vuillemin introduced the term “antibiosis”, which meant “against life”. He used this term to explain the properties of early antibacterial drugs. The actual term “antibiotics” was first employed by Selman Waksman in 1942 to explain the inhibitory effects of drugs produced by microorganisms to other microorganisms. The first antibiotic was discovered by Alexander Fleming in the year 1928 while working on the influenza virus.
Uses of Antibiotics
Today, the name antibiotic is synonymous for drugs that kill bacteria. And as a result, there has been an increased lifespan along with a reduction in the mortality rates.
These microbial infections can wipe out a whole population of organisms which can adversely affect the ecosystem. For instance, anthrax may be a disease that infects livestock and may spread to humans, which is usually fatal unless it's treated.
Prevention against any microorganism’s growth can be done through antimicrobial therapy. However, it might not stop the damage that is already done. For example, the anthrax-causing bacterium Bacillus anthracis doesn't actually kill the host, instead, it's the toxins that are produced which does the deed. Although the bacteria might get killed due to antibiotics, the toxins still remain in the body which can cause damage.
Nowadays, there are two types of antimicrobial therapies available:
Microbicidal therapy – It helps to kill the microorganisms.
Microbiostatic therapy – It helps to prevent microorganism growth.
Examples of Antibiotics
Penicillin
Penicillin was the first ever “true” antibiotic and it had been discovered by a Scottish bacteriologist, Fleming in 1928 to treat plague and several other bacterial infections. Ironically, Penicillin was an accidental discovery, but it had been a landmark discovery within the field of drugs. It is made from Penicillium notatum, which is a mould.
Types of Penicillin
There are different types of penicillin, which are grouped based on their effectiveness.
Penicillin VK and Penicillin G are natural Penicillin.
Penicillin VK is used against several bacterial infections such as ear infections.
Penicillin G is used against several bacterial infections caused by gram-positive and gram-negative cocci. Example: susceptible bacterial infections in the stomach.
Quinolones
They are the type of antibiotics that have the ability to inhibit or kill the growth of bacteria. Developed in 1962, quinolones are made up of an artificial compound called NegGram. Quinolones are used as a treatment against the urinary tract bacterial infections, sinusitis, bronchitis, and pneumonia.
Strain Improvement in Antibiotic or Drug Production
Genetic engineering is a set of techniques that are used to modify the biological characteristics of various living organisms. Example: Recombinant DNA technology, Microinjection, etc. A technique that helps to produce genetically improved strains of antibiotics is called the R-DNA technology or recombinant DNA technology.
The wild strain of microorganisms is transformed into the mutant strain so as to extend the yield and quality of antibiotics. The improvement of biosynthetic pathway design and recombinant deoxyribonucleic acid techniques are often achieved so as to enhance antibiotic production.
Role of Antibodies in Antibiotics
Antibody that is also commonly called immunoglobulin is produced by our immune system. This is produced as a form of protective protein to protect our immune system from any foreign substance. This foreign substance is called an antigen. Antibodies, recognize and attack ntigens in order to remove them from the body. They bind to foreign particles and invade them. As foreign particles are always attacked by antibodies, these antibodies work against these antigens.
Antigens are known to be foreign pathogens that invade the body. It binds with the antibodies and produces a response from our immunity system by grouping up with a large molecule. Hence, the invasion of antigens stimulates the production of antibodies by the immune system.
FAQs on Antibiotics: Definition, Types, and Uses in Biology
1. What are antibiotics and what is their main function in medicine?
Antibiotics are powerful medicines specifically designed to fight bacterial infections. Their main function is to either kill bacteria directly (bactericidal) or stop them from multiplying (bacteriostatic), allowing the body's immune system to clear the infection. They are derived from microorganisms like fungi and bacteria.
2. How do antibiotics actually work to stop a bacterial infection?
Antibiotics work by targeting specific structures or processes unique to bacterial cells. For example, some antibiotics, like penicillin, disrupt the formation of the bacterial cell wall, causing the bacterium to burst. Others may interfere with critical processes like protein synthesis or DNA replication, effectively shutting down the bacteria's ability to survive and reproduce.
3. What are the main types or classes of antibiotics?
There are several major classes of antibiotics, grouped by their chemical structure and mechanism of action. Some common types include:
- Penicillins: Often used for skin, chest, and urinary tract infections.
- Tetracyclines: Used for a wide range of infections, including acne and respiratory issues.
- Macrolides: A common alternative for patients with penicillin allergies, used for lung and chest infections.
- Cephalosporins: Used for more serious infections like meningitis and septicemia.
- Fluoroquinolones: Broad-spectrum antibiotics used for urinary and respiratory infections.
4. Why are antibiotics ineffective against viral infections like the flu or a common cold?
Antibiotics are designed to target the unique machinery of bacterial cells, such as their cell walls. Viruses are structured differently and lack these targets. Instead, viruses replicate by taking over our own host cells. Using antibiotics for a viral infection is ineffective and can contribute to the development of antibiotic resistance.
5. What is the difference between a broad-spectrum and a narrow-spectrum antibiotic?
The difference lies in the range of bacteria they affect. A broad-spectrum antibiotic is effective against a wide variety of bacterial types. A narrow-spectrum antibiotic targets only a few specific types of bacteria. Doctors often prefer narrow-spectrum antibiotics when the specific bacterium is known, as it reduces damage to the body's beneficial bacteria.
6. How does antibiotic resistance develop in bacteria?
Antibiotic resistance is a natural process of evolution. When an antibiotic is used, most bacteria are killed, but some with random mutations may survive. These survivors then multiply, creating a new population of bacteria that is resistant to the drug. Overuse and misuse of antibiotics accelerate this process of natural selection, making infections harder to treat.
7. Why is it so important to complete the full course of antibiotics, even after you start feeling better?
Feeling better doesn't mean all infectious bacteria are eliminated. Some may still be present in your body. Stopping a course early allows these stronger, more resilient bacteria to survive and multiply. This can cause the infection to return and contributes to the spread of antibiotic resistance, making future infections harder to treat for everyone.
8. Where do most antibiotics originally come from?
Many of the most important antibiotics are derived from natural sources. They are chemical weapons produced by microorganisms to compete with other microbes in their environment. For example, Penicillin was famously discovered from the Penicillium fungus, and many others are isolated from soil-dwelling bacteria like the genus Streptomyces.
