Antibiotics: Types and Mechanism

• Antibiotics are a type of antimicrobial substance active against bacteria and are the most important type of antibacterial agent for fighting bacterial infections.
• Antibiotic medications are used to treat bacterial infections.
• Antibiotics are ineffective against viral infections, such as the common cold or influenza.
• Antibiotics can be taken orally, topically, or intravenously.

Mechanism of Action

• Antibiotics work by targeting essential bacterial processes.
• Inhibition of cell wall synthesis: Some antibiotics prevent bacteria from building cell walls, leading to cell death.
• Inhibition of protein synthesis: Other antibiotics interfere with the production of proteins, disrupting bacterial function.
• Inhibition of DNA/RNA synthesis: Certain antibiotics block the synthesis of DNA or RNA, preventing bacterial replication.
• Disruption of metabolic pathways: Some antibiotics target specific metabolic pathways essential for bacterial survival.

Spectrum of Activity

• Antibiotics vary in their spectrum of activity.
• Broad-spectrum antibiotics are effective against a wide range of bacteria.
• Narrow-spectrum antibiotics target specific types of bacteria.
• The choice of antibiotic depends on the type of infection and the bacteria causing it.

Classification of Antibiotics

• Beta-Lactams (e.g., Penicillin, Cephalosporins)
  • Inhibit bacterial cell wall synthesis.
  • Effective against a broad range of bacteria.
• Macrolides (e.g., Erythromycin, Azithromycin)
  • Inhibit bacterial protein synthesis.
  • Often used for respiratory and skin infections.
• Tetracyclines (e.g., Doxycycline, Minocycline)
  • Inhibit bacterial protein synthesis.
  • Used for a variety of infections, including acne and Lyme disease.
• Fluoroquinolones (e.g., Ciprofloxacin, Levofloxacin)
  • Inhibit bacterial DNA replication.
  • Effective against a broad range of bacteria, but use is limited due to side effects and resistance.
• Aminoglycosides (e.g., Gentamicin, Tobramycin)
  • Inhibit bacterial protein synthesis.
  • Used for severe infections, often administered intravenously.

Antibiotic Resistance

• Antibiotic resistance occurs when bacteria evolve to become resistant to antibiotics.
• Overuse and misuse of antibiotics contribute to the development of resistance.
• Resistant bacteria can spread and cause infections that are difficult to treat.
• Antibiotic resistance is a major global health threat.
• Mechanisms of antibiotic resistance
  • Enzymatic inactivation: Bacteria produce enzymes that break down antibiotics.
  • Target modification: Bacteria alter the structure of the antibiotic target, preventing binding.
  • Efflux pumps: Bacteria pump antibiotics out of the cell.
  • Reduced permeability: Bacteria decrease the uptake of antibiotics.
• Strategies to combat antibiotic resistance
  • Antibiotic stewardship: Using antibiotics appropriately and only when necessary.
  • Infection prevention: Implementing measures to prevent the spread of infections.
  • Development of new antibiotics: Researching and developing new antibiotics to combat resistant bacteria.
  • Diagnostic testing: Identifying the specific bacteria causing an infection to guide antibiotic selection.

Common Uses of Antibiotics

• Bacterial pneumonia: Antibiotics are used to treat pneumonia caused by bacteria.
• Urinary tract infections (UTIs): Antibiotics are commonly used to treat UTIs.
• Skin infections: Antibiotics can be used to treat bacterial skin infections, such as cellulitis.
• Strep throat: Antibiotics are used to treat strep throat caused by Streptococcus bacteria.
• Sepsis: Antibiotics are a critical component of treating sepsis, a life-threatening condition caused by infection.

Side Effects of Antibiotics

• Common side effects include nausea, vomiting, diarrhea, and abdominal pain.
• Antibiotics can disrupt the normal balance of bacteria in the gut, leading to gastrointestinal issues.
• Allergic reactions can occur with some antibiotics.
• Some antibiotics can cause more serious side effects, such as kidney damage or hearing loss.
• Clostridium difficile infection (CDI) is a serious complication that can occur after antibiotic use.
• Photosensitivity: Some antibiotics can increase sensitivity to sunlight.

Important Considerations

• Take antibiotics exactly as prescribed.
• Complete the full course of antibiotics, even if you start feeling better.
• Do not share antibiotics with others.
• Do not save antibiotics for future use.
• Inform your healthcare provider of any allergies or other medications you are taking.
• Probiotics may help restore the balance of gut bacteria after antibiotic use.

Novel Approaches

• Phage therapy: Using bacteriophages (viruses that infect bacteria) to treat bacterial infections.
• Antimicrobial peptides: Developing synthetic peptides that kill bacteria.
• Immunomodulatory therapies: Enhancing the body's immune response to fight bacterial infections.
• CRISPR-based antimicrobials: Using CRISPR technology to target and kill bacteria.
• Nanoparticle-based antibiotics: Delivering antibiotics directly to bacterial cells using nanoparticles.