Drugs Used to Treat Infections Flashcards
(10 cards)
Penicillins
Mechanism of Action:
- Bactericidal: Disrupts bacterial cell wall synthesis.
- Contains a beta-lactam ring responsible for antibacterial activity.
Uses:
- Effective against gram-positive bacteria (e.g., Staphylococci, Streptococci).
- Some gram-negative bacteria.
Types:
- Penicillin G (prototype)
- Penicillinase-resistant: Oxacillin.
- Broad-spectrum: Ampicillin, Amoxicillin.
- Extended-spectrum: Piperacillin (targets more species).
Adverse Effects:
- Allergic reactions: Rash, pruritus (itching), fever.
- Cross-reactivity: Allergy to one increases risk with others in the class.
- Minor GI symptoms possible.
Cephalosporins
Mechanism of Action:
- Bactericidal: Inhibits bacterial cell wall synthesis.
- Also contains a beta-lactam ring.
Uses:
- Gram-negative infections.
Penicillin alternative for allergic patients.
Generations:
- 1st Gen: Gram-positive (e.g., Staphylococci, Streptococci), prototype Cefazolin (Ancef).
- 2nd Gen: More resistant to beta-lactamase enzymes.
- 3rd Gen: Resistant to beta-lactamase; used for Pseudomonas, Salmonella.
- 4th/5th Gen: Effective against MRSA infections.
Adverse Effects:
- Allergic reactions: Similar to penicillins.
- Cross-sensitivity: 5–10% of penicillin-allergic patients may react.
Tetracyclines
Mechanism of Action:
- Bacteriostatic: Inhibits bacterial protein synthesis by binding to ribosomes.
Uses:
- H. pylori, Chlamydia infections.
- Acne vulgaris: Topical or low-dose oral use.
- Rarely prescribed due to resistance.
Adverse Effects:
- GI issues: Nausea, vomiting, diarrhea.
- Photosensitivity: Severe skin reactions with sun exposure.
- Teeth discoloration: Permanent yellow-brown in children <8 years.
- Reduced absorption with calcium/iron.
-High risk of superinfection.
Prototype: Tetracycline.
Macrolides
Mechanism of Action:
- Inhibits protein synthesis:
+ Bacteriostatic at low doses.
+ Bactericidal at high doses.
Uses:
- Broad-spectrum: Effective against gram-positive and some gram-negative bacteria.
- C. difficile infections: Fidaxomicin.
Adverse Effects:
- GI distress: Nausea, diarrhea, abdominal pain.
- Superinfections possible.
Prototype: Erythromycin.
Note: Newer macrolides = longer half-life, less gastric irritation
Aminoglycosides
Mechanism of Action:
- Bactericidal: Inhibits bacterial protein synthesis.
Uses:
- Serious systemic infections: Aerobic gram-negative bacteria (E. coli, Pseudomonas, Serratia).
- Administered parenterally (poor GI absorption).
Adverse Effects:
- Ototoxicity: Hearing loss, dizziness, balance issues, tinnitus.
- Nephrotoxicity: Kidney damage, abnormal urine tests.
Prototype: Gentamicin.
Fluoroquinolones
Mechanism of Action:
- Bactericidal: Inhibits bacterial DNA replication enzymes.
Uses:
- Infections: GI, respiratory, genitourinary tract, skin, soft tissue.
Adverse Effects: GI symptoms: Nausea, vomiting, diarrhea.
Prototype: Ciprofloxacin (Cipro®).
Sulfonamides
Mechanism of Action:
- Bacteriostatic: Inhibits folic acid synthesis (essential for DNA/RNA synthesis).
Uses:
- Broad-spectrum: Active against gram-positive & gram-negative bacteria.
- UTIs, Pneumocystis pneumonia, Inflammatory bowel disease (Sulfasalazine).
- Urinary antiseptics: Nitrofurantoin (acts locally in urinary tract).
Adverse Effects:
- Mild reactions: Nausea, vomiting.
- Hypersensitivity: Rash, allergic reactions.
Prototype: Trimethoprim-sulfamethoxazole (Septra).
clindamycin
Uses: Both gram-positive & gram-negative infections.
Note: Used when safer antibiotics aren’t effective.
metronidazole (Flagyl)
Uses:
- Anaerobic bacteria: Abscesses, gangrene, diabetic ulcers, deep infections.
- H. pylori (peptic ulcers), parasites.
Adverse Effects: Dry mouth (minor side effect).
Vancomycin
Uses:
- Severe gram-positive infections.
- MRSA treatment (most effective drug).
Adverse Effects:
- Ototoxicity: Hearing damage.
- Nephrotoxicity: Kidney issues.
