28/06/2025
1. What Are Antibiotics?
Antibiotics are drugs used to treat bacterial infections. They either:
• Kill bacteria (bactericidal) or
• Inhibit bacterial growth (bacteriostatic)
They are ineffective against viral, fungal, or parasitic infections.
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2. Classification of Antibiotics
Antibiotics can be classified in various ways:
A. By Mechanism of Action
1. Inhibit Cell Wall Synthesis
• Examples: Penicillins, Cephalosporins, Carbapenems, Vancomycin
• Effect: Bactericidal
2. Disrupt Cell Membrane
• Examples: Polymyxins, Daptomycin
• Effect: Bactericidal
3. Inhibit Protein Synthesis
• Examples:
• 30S inhibitors: Tetracyclines, Aminoglycosides
• 50S inhibitors: Macrolides, Clindamycin, Chloramphenicol
• Effect: Mostly bacteriostatic
4. Inhibit Nucleic Acid Synthesis
• Examples: Fluoroquinolones (DNA gyrase inhibitors), Rifampin (RNA polymerase)
• Effect: Bactericidal
5. Antimetabolites (Inhibit Folate Synthesis)
• Examples: Sulfonamides, Trimethoprim
• Effect: Bacteriostatic or bactericidal (in combination)
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B. By Spectrum of Activity
1. Broad-spectrum
• Effective against both Gram-positive and Gram-negative bacteria
• Examples: Amoxicillin-clavulanate, Tetracyclines, Carbapenems
2. Narrow-spectrum
• Target specific bacteria
• Examples: Penicillin G (Gram-positive), Aztreonam (Gram-negative)
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C. By Chemical Structure
1. Beta-lactams: Penicillins, Cephalosporins, Carbapenems, Monobactams
2. Aminoglycosides: Gentamicin, Amikacin
3. Macrolides: Erythromycin, Azithromycin
4. Tetracyclines: Doxycycline, Minocycline
5. Quinolones/Fluoroquinolones: Ciprofloxacin, Levofloxacin
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3. Commonly Used Antibiotics and Their Uses
Number 3 is the picture below ⬇️
4. Side Effects of Antibiotics
• Common:
• Diarrhea
• Nausea, vomiting
• Allergic reactions (rash, anaphylaxis)
• Yeast infections (candida overgrowth)
• Serious:
• Clostridioides difficile infect