What are antibiotics and how do they work against bacteria
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 in Biology Structure Types and Functions
1. What are antibiotics?
Antibiotics are antimicrobial drugs that kill or inhibit the growth of bacteria. They are used to treat bacterial infections in humans, animals, and sometimes plants. Antibiotics do not work against viruses.
- Target specific bacterial structures or processes
- Can be natural (from fungi or bacteria) or synthetic
- Commonly prescribed for infections like strep throat, urinary tract infections, and pneumonia
2. How do antibiotics work in the body?
Antibiotics work by targeting essential bacterial structures or metabolic pathways, leading to bacterial death or growth inhibition. Different classes act in specific ways:
- Block cell wall synthesis (e.g., penicillin)
- Inhibit protein synthesis at bacterial ribosomes
- Disrupt DNA replication or transcription
- Interfere with key metabolic pathways
3. What is the difference between bactericidal and bacteriostatic antibiotics?
The main difference is that bactericidal antibiotics kill bacteria directly, while bacteriostatic antibiotics stop bacteria from multiplying.
- Bactericidal: Cause bacterial cell death (e.g., damage to cell wall)
- Bacteriostatic: Inhibit growth, allowing the immune system to eliminate bacteria
4. Why don’t antibiotics work against viruses?
Antibiotics do not work against viruses because viruses lack the cellular structures and metabolic pathways that antibiotics target. Viruses use host cells to replicate and do not have:
- A cell wall
- Independent ribosomes
- Self-contained metabolism
5. What is antibiotic resistance?
Antibiotic resistance is the ability of bacteria to survive and grow despite the presence of an antibiotic that normally kills them. It occurs due to:
- Genetic mutations in bacterial DNA
- Acquisition of resistance genes via horizontal gene transfer
- Overuse or misuse of antibiotics
6. How do bacteria become resistant to antibiotics?
Bacteria become resistant through genetic changes that reduce or block the antibiotic’s effect. Key mechanisms include:
- Producing enzymes that inactivate the drug (e.g., beta-lactamase)
- Altering the drug’s target site
- Reducing drug entry or increasing efflux pumps
- Acquiring resistance genes through plasmids
7. What are broad-spectrum and narrow-spectrum antibiotics?
Broad-spectrum antibiotics act against a wide range of bacteria, while narrow-spectrum antibiotics target specific types.
- Broad-spectrum: Effective against both Gram-positive and Gram-negative bacteria
- Narrow-spectrum: Target specific bacterial groups
8. What is the role of antibiotics in medicine?
The role of antibiotics in medicine is to treat and prevent bacterial infections and reduce infection-related mortality. They are used to:
- Treat acute infections such as pneumonia and tuberculosis
- Prevent infections during surgery (prophylaxis)
- Protect immunocompromised patients
9. Can antibiotics affect the normal microbiota?
Yes, antibiotics can disrupt the body’s normal microbiota by killing beneficial bacteria along with harmful ones. This imbalance may lead to:
- Digestive issues such as diarrhea
- Overgrowth of pathogens like Clostridioides difficile
- Reduced microbial diversity
10. Who discovered antibiotics?
The first true antibiotic, penicillin, was discovered by Alexander Fleming in 1928. He observed that the fungus Penicillium notatum inhibited bacterial growth.
- Marked the beginning of modern antibiotic therapy
- Later developed for clinical use by Howard Florey and Ernst Chain
- Revolutionized treatment of bacterial diseases
