Untitled Quiz

Classifying Antibiotics

• Antibiotics can be classified based on their mechanism of action.
• Bactericidal antibiotics kill bacteria directly, while bacteriostatic antibiotics inhibit bacterial growth.
• Bactericidal antibiotics include:
  • Penicillins
  • Cephalosporins
  • Aminoglycosides
  • Fluoroquinolones
  • Metronidazole
• Bacteriostatic antibiotics include:
  • Tetracyclines
  • Macrolides
  • Chloramphenicol
  • Sulfonamide

How Bacteriostatic Drugs Work

• Bacteriostatic drugs work by inhibiting various cellular processes essential for bacterial survival, including:
  • Protein synthesis: blocking the production of key proteins needed for bacterial function.
  • Nucleic acid synthesis: interfering with the replication and transcription of bacterial DNA and RNA.
  • Metabolic pathways: disrupting essential metabolic processes like folate synthesis.

Whole Classification of Antibiotics

• Antibiotics can be broadly categorized into four main groups:
  • Beta-lactam antibiotics:
    • Penicillins
    • Cephalosporins
    • Carbapenems
    • Monobactams
  • Inhibitors of nucleic acid synthesis:
    • Fluoroquinolones
    • Rifampin
  • Protein synthesis inhibitors:
    • Tetracyclines
    • Macrolides
    • Aminoglycosides
  • Metabolic pathway inhibitors:
    • Sulfonamides
    • Trimethoprim

Oral Drugs Given in Pregnancy

• Some antibiotics considered safe for use during pregnancy include:
  • Penicillins
  • Cephalexin and Ceftriaxone
  • Erythromycin
  • Clindamycin

Penicillins

• Penicillins belong to the beta-lactam antibiotic class.
• They are cell wall synthesis inhibitors, effectively targeting Gram-positive, Gram-negative bacteria, and spirochetes.
• Common indications for penicillin use include:
  • Streptococcal infections
  • Pneumococcal infections
  • Syphilis

Penicillin Classification & Mechanism of Action

• Penicillins are classified into different categories based on their spectrum of activity and resistance to penicillinase:
  • Narrow spectrum: Penicillinase-susceptible (Penicillin G and V)
  • Extended spectrum:
    • Penicillinase-sensitive penicillins: Amoxicillin, Ampicillin, Piperacillin
    • Penicillinase-resistant penicillins: Nafcillin, Oxacillin, Dicloxacillin
• Mechanism of action:
  • Penicillins bind to penicillin-binding proteins (PBPs) in the bacterial cell membrane.
  • This inhibits the transpeptidation reaction, a crucial step in bacterial cell wall synthesis.

Penicillin Adverse Effects

• Potential adverse effects of penicillins include:
  • IgG-mediated hemolysis
  • Interstitial nephritis
  • Anaphylaxis

Significance of the Beta-Lactam Ring

• The beta-lactam ring in penicillin is essential for its antibacterial activity.
• Its structure resembles the D-alanyl-D-alanine portion of peptidoglycan, the building block of bacterial cell walls.
• This similarity allows beta-lactams to bind to and inhibit PBPs, disrupting cell wall formation.
• Destruction of the beta-lactam ring leads to bacterial resistance.

Increasing Beta-Lactam Activity

• To enhance the efficacy of beta-lactam antibiotics and combat bacterial resistance, inhibitors of beta-lactamases can be added.
• These inhibitors, such as sulbactams, tazobactams, or clavulanic acid, prevent bacteria from degrading the antibiotic.

Vancomycin

• Mode of Action: Similar to beta-lactams, Vancomycin inhibits peptidoglycan synthesis.
• Indications: Vancomycin is a narrow-spectrum antibiotic used for:
  • Serious drug-resistant infections like Methicillin-resistant Staphylococcus aureus (MRSA)
  • Combination therapy with ceftriaxone for penicillin-resistant Streptococcus pneumoniae (PRSP)
  • Backup treatment for Clostridium difficile infections.
• Side effects:
  • Chills
  • Fever
  • Phlebitis
  • Ototoxicity
  • Nephrotoxicity
  • Red Man syndrome (with rapid IV infusion)

Red Man Syndrome

• Red Man syndrome is a hypersensitivity reaction to rapid intravenous vancomycin administration.
• It is characterized by flushing and redness of the skin, due to the swift release of histamine.

What is an antibiotic?

• Antibiotics are substances, either naturally produced by microorganisms or synthetically derived, that selectively kill or inhibit the growth of other microorganisms.

Bactericidal Effect

• A bactericidal effect refers to the complete destruction of bacterial cells.