Antibiotics: Penicillin and Cephalosporin

Classification and Structure

• Penicillin and Cephalosporin are beta-lactam antibiotics
• Consist of a beta-lactam ring and a side chain
• Differ in the structure of the side chain and the way they are produced

Mechanism of Action

• Inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)
• Interfere with the final stage of bacterial cell wall formation
• Cause bacterial lysis and death

Penicillin

• Discovered by Alexander Fleming in 1928
• Produced by the fungus Penicillium chrysogenum
• Effective against Gram-positive bacteria
• Examples of penicillin antibiotics:
  • Penicillin G (benzylpenicillin)
  • Penicillin V (phenoxymethylpenicillin)
  • Amoxicillin

Cephalosporin

• Developed from the fungus Cephalosporium
• Effective against both Gram-positive and Gram-negative bacteria
• Examples of cephalosporin antibiotics:
  • Cephalexin
  • Ceftriaxone
  • Ceftazidime

Resistance

• Bacteria can develop resistance to penicillin and cephalosporin through:
  • Beta-lactamase enzymes that break down the beta-lactam ring
  • Alterations in PBPs to reduce antibiotic binding
  • Changes in cell wall structure to reduce antibiotic penetration

Clinical Use

• Used to treat a wide range of bacterial infections, including:
  • Respiratory tract infections
  • Skin and soft tissue infections
  • Urinary tract infections
  • Meningitis and sepsis

Beta-Lactam Antibiotics

• Penicillin and Cephalosporin are beta-lactam antibiotics, characterized by a beta-lactam ring and a side chain
• They differ in their side chain structure and production methods

Mechanism of Action

• Inhibit bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs)
• Interfere with the final stage of bacterial cell wall formation, causing bacterial lysis and death

Penicillin

• Discovered by Alexander Fleming in 1928
• Produced by the fungus Penicillium chrysogenum
• Effective against Gram-positive bacteria
• Examples: Penicillin G (benzylpenicillin), Penicillin V (phenoxymethylpenicillin), Amoxicillin

Cephalosporin

• Developed from the fungus Cephalosporium
• Effective against both Gram-positive and Gram-negative bacteria
• Examples: Cephalexin, Ceftriaxone, Ceftazidime

Antibiotic Resistance

• Bacteria develop resistance through:
  • Beta-lactamase enzymes that break down the beta-lactam ring
  • Alterations in PBPs to reduce antibiotic binding
  • Changes in cell wall structure to reduce antibiotic penetration

Clinical Applications

• Used to treat various bacterial infections, including:
  • Respiratory tract infections
  • Skin and soft tissue infections
  • Urinary tract infections
  • Meningitis and sepsis

Learn about the structure and mechanism of action of beta-lactam antibiotics, including penicillin and cephalosporin, and how they inhibit bacterial cell wall synthesis.