Inhibitors of Cell Wall Synthesis
These antibiotics target the bacterial cell wall, leading to lysis and death.
Beta-lactams: Interfere with peptidoglycan synthesis by inhibiting penicillin-binding proteins (PBPs).
Examples:
- Penicillins: Amoxicillin, Penicillin G.
- Cephalosporins: Ceftriaxone, Cefuroxime.
- Carbapenems: Imipenem, Meropenem.
- Monobactams: Aztreonam.
Glycopeptides: Bind to peptidoglycan precursors, preventing cross-linking.
Examples: Vancomycin, Teicoplanin.
Others: Bacitracin (used topically).
Inhibitors of Protein Synthesis
These antibiotics target bacterial ribosomes, disrupting protein synthesis.
A. 30S Ribosomal Subunit Inhibitors
Aminoglycosides: Cause misreading of mRNA.
Examples: Gentamicin, Amikacin, Tobramycin.
Tetracyclines: Block tRNA attachment.
Examples: Tetracycline, Doxycycline, Minocycline.
B. 50S Ribosomal Subunit Inhibitors
Macrolides: Inhibit translocation.
Examples: Erythromycin, Azithromycin, Clarithromycin.
Lincosamides: Inhibit peptide bond formation.
Examples: Clindamycin, Lincomycin.
Oxazolidinones: Inhibit the initiation complex.
Example: Linezolid.
Chloramphenicol: Broad-spectrum, inhibits peptidyl transferase.
Inhibitors of Nucleic Acid Synthesis
Target bacterial DNA or RNA, affecting replication or transcription.
Fluoroquinolones: Inhibit DNA gyrase and topoisomerase IV.
Examples: Ciprofloxacin, Levofloxacin, Moxifloxacin.
Rifamycins: Inhibit RNA polymerase.
Examples: Rifampin, Rifabutin.
Metronidazole: Causes DNA damage in anaerobic bacteria and protozoa.
Antimetabolites (Folic Acid Synthesis Inhibitors)
Inhibit bacterial folate synthesis, essential for DNA and RNA production.
Sulfonamides: Compete with PABA.
Example: Sulfamethoxazole.
Trimethoprim: Inhibits dihydrofolate reductase.
Example: Co-trimoxazole (Sulfamethoxazole + Trimethoprim).
Disruptors of Cell Membrane Integrity
Cause bacterial cell leakage, leading to death.
Polymyxins: Bind to lipopolysaccharides, disrupting membranes of Gram-negative bacteria.
Examples: Polymyxin B, Colistin.
Lipopeptides: Create pores in the membrane.
Example: Daptomycin.
Miscellaneous Antibiotics
Nitrofurans: Damages bacterial DNA.
Example: Nitrofurantoin (used for urinary tract infections).
Fidaxomicin: Targets RNA polymerase, used for Clostridioides difficile infections.
Fosfomycin: Inhibits cell wall synthesis by blocking an enzyme (MurA).
Classification by Spectrum of Activity
Broad-spectrum antibiotics: Effective against a wide range of bacteria (e.g., Tetracyclines, Chloramphenicol).
Narrow-spectrum antibiotics: Target specific types of bacteria (e.g., Penicillin G, Vancomycin).
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