Antibiotics Flashcards
What is the mechanism of action of penicillins?
Penicillins bind to penicillin-binding proteins (PBPs), inhibit the transpeptidation reaction with peptidoglycan in the cell wall, weakening the wall and stopping synthesis.
What are the clinical uses of Penicillin G?
Penicillin G is used for oropharyngeal, meningitis, STI, endocarditis, and is the drug of choice for syphilis.
What side effects are associated with the use of Penicillins?
Common side effects include hypersensitivity reactions, seizures (only for oral dosing), nausea, vomiting, diarrhea, and opportunistic fungal infections.
Describe the spectrum and dosing considerations for Amoxicillin.
Amoxicillin covers Gram-positive cocci and some Enteric Gram-negative bacilli. It is used for HEENT infections like otitis media, sinusitis, and pharyngitis. Pediatric dosing for otitis media is 80-90mg/kg divided BID-TID.
How does resistance to penicillins occur?
Resistance to penicillins often occurs through the production of penicillinase, an enzyme that inactivates the antibiotic.
What is the role of Cephalosporins in bacterial infections?
Cephalosporins bind to penicillin-binding proteins on the cytoplasmic membrane, inhibit transpeptidation reactions that cross-link peptidoglycan chains in the cell wall, thus breaking them and inhibiting cell wall synthesis.
List some key side effects of Cephalosporins.
Key side effects of cephalosporins include hypersensitivity reactions, gastrointestinal issues, seizures, and a potential for cross-reactivity with penicillin in cases of penicillin allergy.
What are the indications for using Vancomycin and its side effects?
Vancomycin is indicated for MRSA/MRSE infections, meningitis, and is also used as a backup drug for GI infections like Clostridioides difficile. Side effects include ‘red man syndrome’, ototoxicity, nephrotoxicity, and potential toxicity requiring monitoring of lab values.
Explain the action of Aminoglycosides and their usage.
Aminoglycosides bind to the 30S ribosomal subunit, causing a change at the genetic level which interrupts protein synthesis. They are used primarily for Gram-negative bacterial infections and certain mycobacterial diseases like tuberculosis.
What are the clinical implications of antibiotic resistance in Fluoroquinolones?
Resistance in fluoroquinolones usually involves gene mutations that alter the target enzymes (DNA gyrase and topoisomerase IV), diminishing the drug’s effectiveness in treating infections.
What are the common dosing and side effects of Azithromycin?
Azithromycin dosing typically involves 500mg on day 1 followed by 250mg for days 2-5 for respiratory infections. Common side effects include gastrointestinal upset, decreased risk of prolonged QT interval, and interactions with hepatic enzymes.
