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