Antimicrobials

• Antimicrobial

  An agent that kills microorganisms or stops their growth
• Main types of antimicrobial agents

  • Antibiotics
  • Antifungals
  • Antivirals
  • Antiparasitics
• β-lactams


  • Penicillins
  • Cephalosporins
  • Carbapenems
• Penicillins


  • Natural Penicillins: Penicillin V, Penicillin G
  • Penicillinase-resistant Penicillins: Flucloxacillin, Dicloxacillin
  • Aminopenicillins: Amoxicillin, Ampicillin
  • Penicillin + β-lactamase Inhibitors: Amoxicillin + Clavulanic acid, Piperacillin + Tazobactam
• Cephalosporins


  • 1st Generation: Good for Gram-positive coverage
  • 3rd Generation: Covers Streptococcus and common Gram-negative bacteria
• Carbapenems


  • Imipenem, Meropenem, Ertapenem
• Carbapenems


  Used for ESBL-producing organisms and broad coverage but excluding MRSA
• Glycopeptides


  • Vancomycin, Teicoplanin
• Glycopeptides


  Used for Gram-positive bacteria, including MRSA
• Aminoglycosides


  • Amikacin, Gentamicin, Tobramycin
• Aminoglycosides


  Used for severe Gram-negative infections
• Quinolones


  • Ciprofloxacin, Norfloxacin, Moxifloxacin
• Quinolones


  Used for a variety of infections including UTIs, and respiratory infections
• Macrolides


  • Azithromycin, Clarithromycin, Erythromycin
• Macrolides


  Used for respiratory infections, atypical bacterial infections, and as alternatives for penicillin-allergic patients
• Tetracyclines


  • Tetracycline, Minocycline, Doxycycline
• Tetracyclines


  Used for a variety of infections including those caused by atypical bacteria
• Antifolate Drugs


  • Sulfamethoxazole, Trimethoprim
• Antifolate Drugs


  Used mainly for UTIs and infections caused by certain Gram-negative bacteria
• Nitroimidazoles


  • Metronidazole, Tinidazole
• Nitroimidazoles


  Used for anaerobic bacterial infections and protozoal infections
• Lincosamides


  • Clindamycin, Lincomycin
• Lincosamides


  Used for Gram-positive and anaerobic bacterial infections
• Rational Use


  Use the narrowest spectrum antibiotic that is effective
• De-escalation


  Start with broad-spectrum antibiotics if necessary and switch to narrower-spectrum antibiotics based on culture results
• Duration


  Limit the duration of antibiotic therapy to the shortest effective course
• Combination Therapy


  Use combination therapy to prevent resistance in certain cases
• Monitoring


  Regularly monitor patient response and adjust therapy as needed
• Common adverse drug reactions

  • Allergic reactions, gastrointestinal upset (β-lactams)
  • Nephrotoxicity, ototoxicity, Redman syndrome (Glycopeptides)
  • Nephrotoxicity, ototoxicity (Aminoglycosides)
  • Peripheral neuropathy, tendon damage (Quinolones)
  • Gastrointestinal upset, QT interval prolongation (Macrolides)
  • Photosensitivity, gastrointestinal upset, epigastric burning (Tetracyclines)
  • Peripheral neuropathy, disulfiram-like reaction with alcohol (Nitroimidazoles)
  • Risk of C. difficile-associated disease (Lincosamides)
• Vancomycin Monitoring


  Measure AUC or trough level in patients on therapy for >48 hours to prevent underdosing and toxicity
• Aminoglycosides Monitoring


  1. Monitor therapeutic drug levels in patients on therapy for >48 hours to prevent toxicity

  2. Trough concentrations should be checked, but AUC is preferred
• Relevant patient education points

  • Adherence: Stress the importance of completing the full course of antibiotics even if they feel better
  • Side Effects: Educate about potential side effects and when to seek medical advice
  • Interactions: Inform about possible drug and food interactions (e.g., antacids, dairy products with tetracyclines)
  • Specific Instructions: For instance, taking tetracyclines with food to reduce stomach upset, remaining upright for 30 minutes after taking doxycycline to prevent esophageal irritation, and avoiding alcohol with metronidazole to prevent a disulfiram-like reaction
  • Preventing Resistance: Encourage appropriate use to prevent antibiotic resistance, including not using antibiotics for viral infections like colds and flu