Antibiotics Classification: Examples, Chart, FAQs

Since their discovery, antibiotics have undoubtedly transformed modern medicine into the contemporary successful treatment of bacterial infections that claimed so many lives before. From penicillin in the 1920s to the wide array of antibiotic classes in use today, these drugs rewrote how infectious diseases are treated. All of this may now be lost due to the growing problem of antibiotic resistance, which has made a huge dent in their efficacy.

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This Story also Contains

1. Understanding Antibiotics
2. Types of Antibiotics
3. Real-life relevance and applications
4. Some Solved Examples
5. Summary

Equally important to the meaning of antibiotics, their mechanism of action and their place in history is understanding such. We will explain each of the classes of antibiotics, detailing the mechanism of action, spectrum of activity, and ability for resistance. We will use real examples and case studies to detail why antibiotics play a paramount role in clinical and public health settings.

Understanding Antibiotics

Antibiotics represent very potent medicines designed to combat different kinds of bacterial infections. In principle, they act in two ways: bactericidal antibiotics kill bacteria directly, while the action of bacteriostatic antibiotics consists in slowing down the growth of bacteria until the immune system is able to fight off the infection. The first antibiotic, penicillin, was discovered by Alexander Fleming in 1928 and totally revolutionized medical science. Since then, millions have been saved from various diseases by being treated with antibiotics for small infections to potentially fatal ones.

The importance of antibiotics extends beyond the treatment of individual patients. Without them, surgical operations, cancer treatments, and control of chronic conditions like diabetes and lung disease would be radically different because of the occurrence and severity of infections. Inappropriate and excessive uses of the drugs, however, have paved the way for emerging resistant strains of bacteria against them. This growing crisis engulfs immediate attention from healthcare providers, researchers, and policymakers alike.

The term antibiotics has been derived from the word 'Antibiosis' which means survival of fittest, i.e., a process in which one organism may destroy another to preserve itself. It is a chemical substance produced by or derived from living cells that is capable of inhibiting life processes or even destroying microorganisms.

The first antibiotic, discovered by Alexander Fleming in 1929 from the mold Penicillium notatum, was penicillin. In 1938, Ernst Chain and Howard Florey isolated penicillin in pure form and proved its effectiveness as an antibiotic. It was against the large number of infections caused by various cocci, gram-positive bacteria, etc. It is an effective drug for pneumonia, bronchitis, sore throat, and abscesses.

In penicillin, a four-membered ring is fused to another five-membered ring. Structures of individual penicillins are given in the table. Penicillin-G is the most commonly used. The penicillins are only sparingly soluble in water. However, their sodium or potassium salts are soluble in water. Penicillins are found to be active against gram-positive stains. However, these are ineffective against gram-negative organisms. Organisms sometimes develop resistance to penicillins. Penicillins generally have low toxicity in comparison to sulpha drugs. However, in some cases, allergic reactions may result. Penicillin is thus, given after a test prick.

The antibiotics can either be bactericidal or bacteriostatic. Examples are:

• Bactericidal: The drugs that kill the organism in the body. For example, penicillin, ofloxacin, and aminoglycosides.
• Bacteriostatic: The drugs that inhibit or check the growth of the organism in the body. For example, tetracycline, chloramphenicol, and erythromycin.

Types of Antibiotics

There are several classes of antibiotics according to their chemical structure and mechanism of action. The most frequently prescribed include:

• Penicillins: This class of antibiotics includes many widely used antibiotics, such as amoxicillin and ampicillin, that are indicated for treatment against a wide variety of infections.
• Cephalosporins: Similar to penicillins, they also have a broad spectrum of activity against microbes and are often used preoperatively.
• Aminoglycosides: These are very potent antibiotics reserved mainly for serious infections caused by Gram-negative bacteria.
• Macrolides: Against infections of the respiratory tract, macrolides—of which azithromycin is a noted example—are prescribed for those who show allergies to penicillin.
• Tetracyclines: They are used against a wide array of infections, from acne to respiratory infections.

Most class activities display a characteristic spectrum of activity, side effects, and potential for resistance. Understanding these sections of information from each drug class is valuable in detailing appropriate prescribing and effective treatment outcomes.

Real-life relevance and applications

The role played by antibiotics in real life is simply not possible to overstate. They are useful in treating bacterial infections, preventing infections after surgeries, and in the management of chronic diseases. However, antibiotic resistance has serious concerns for public health. It is estimated that, according to the CDC, each year in the U.S., at least 2 million people get infected with antibiotic-resistant bacteria. This causes more than 23,000 deaths.

As an example, resistant bacteria with infections can complicate once-routine surgical procedures, turning minor operations into matters of life and death. Moreover, the financial cost due to antibiotic resistance is a very heavy one: it involves an increased healthcare cost due to prolonged hospital stays.

It is therefore important to have research in antibiotics and resistance within academia to help develop new treatments and strategies against the crisis. Alternative therapies for conditions where the arsenal of existing antibiotics is limited, such as bacteriophage therapy and novel antimicrobial agents, are being explored by investigators searching for remedies.

Public health campaigns for promoting the rational use of antibiotics, improving sanitation, and increasing infection control are critical to reducing the threat of antibiotic resistance. On this basis, education and awareness campaigns will enable patients and healthcare providers to make a proper decision about the use of antibiotics with a view to preserving these lifesaving drugs.

Some Solved Examples

Example 1: Matching Items

Question:
Match the items in column (I) with the items in column (II):
- (A) Norethindrone
- (B) Ofloxacin
- (C) Equanil

Column (II):
- (P) Antibiotic
- (Q) Anti-fertility
- (R) Hypertension
- (S) Analgesics

Solution:
- Norethindrone is an anti-fertility drug.
- Ofloxacin is an antibiotic.
- Equanil is used for treating hypertension.

So, the correct match is:
- (A) → (Q)
- (B) → (P)
- (C) → (R)

Hence, the answer is option (2).

Example 2: Streptomycin's Effectiveness

Question:
Streptomycin is effective for infections related to:
1. Throat, lungs, fever, and ears.
2. Throat, fever, ears, and lungs.
3. Throat, lungs, ears, and kidneys.
4. Fever, lungs, and ears.

Solution:
Streptomycin is highly effective against tuberculosis and common infections in the throat, lungs, ears, and kidneys.

Therefore, the correct answer is option (3).

Example 3: Drug Interaction with Oral Contraceptives

Question:
The drug which may not interfere with the efficiency of oral contraceptives is:
1. Barbiturates
2. Rifampicin
3. Ampicillin
4. Amoxicillin

Solution:
Rifampicin and barbiturates can lower the effectiveness of oral contraceptives. Ampicillin can also make birth control pills less effective. However, amoxicillin does not interfere with the effectiveness of oral contraceptives.

Hence, the correct answer is option (4).

Example 4: Aminoglycosides Use

Question:
Aminoglycosides are usually used as:
1. Antibiotic
2. Analgesic
3. Hypnotic
4. Anti-fertility

Solution:
Aminoglycosides are commonly used as antibiotics.

Therefore, the correct answer is option (1).

Example 5: Non-Bactericidal Antibiotic

Question:
Which of the following is NOT a bactericidal antibiotic?
1. Penicillin
2. Aminoglycosides
3. 0.03 ppm Cl2
4. Ofloxacin

Solution:
Penicillin, aminoglycosides, and ofloxacin are all bactericidal antibiotics. However, 0.03 ppm Cl2 is a disinfectant, not a bactericidal antibiotic.

Hence, the correct answer is option (3).

Summary

Shortly, antibiotics were gigantic victories of medicine in the treatment of bacterial infections and brought immense improvements in health outcomes in all fields of medicine. Their discovery changed the tide of medical history because it opened an avenue to cure, with great ease, what was considered hitherto to be fatal infections. From penicillin to a variety of classes of antibiotics in current clinical applications, they allowed surgeries and treatment of cancers alongside chronic disease management since they prevented infections.