Antibiotic Mechanisms and Classifications

Comprehensive vocabulary flashcards covering the mechanism of action, clinical uses, and adverse effects of major antibiotic classes based on the lecture transcript.

Bacterial Cell Wall Synthesis Inhibition

The mechanism of action for penicillins where the drug binds to PBPs (Penicillin-Binding Proteins) to prevent the cross-linking of peptidoglycan.

Penicillin G and Penicillin V

Narrow spectrum antibiotics used for Streptococcal infections, Syphilis, and oral flora; Penicillin G is administered IV or IM, while Penicillin V is PO.

Anti-staphylococcal Penicillins

A class including Oxacillin, Dicloxacillin, and Nafcillin that is resistant to penicillinase ($\beta$-lactamase) and used for MSSA infections.

Nafcillin Adverse Effects

Includes hypersensitivity, hepatotoxicity (more than others in its class), interstitial nephritis, and cholestatic jaundice.

Aminopenicillins

Includes Ampicillin and Amoxicillin; active against Enterococcus, Listeria, H. influenzae, E. coli, Proteus, and H. pylori.

Amoxicillin

An aminopenicillin that is better absorbed orally than ampicillin; often combined with clavulanic acid.

Piperacillin

An antipseudomonal penicillin often combined with tazobactam to treat Pseudomonas aeruginosa and polymicrobial infections.

1st Generation Cephalosporins

Drugs like Cefazolin and Cephalexin (Keflex) used for Gram Positive infections (MSSA, streptococci) and surgical prophylaxis; not active against MRSA or Pseudomonas.

Cefoxitin

A 2nd generation cephalosporin (specifically a cephamycin) that provides coverage for Gram negatives and anaerobes.

3rd Generation Cephalosporins

A class including Ceftriaxone (good CNS penetration, once daily dosing) and Ceftazidime (active against Pseudomonas).

Cefepime

A 4th generation cephalosporin with a very broad spectrum covering Gram positive and Gram negative bacteria, including Pseudomonas.

$\beta$-Lactamase Inhibitors

Agents like Sulbactam, Clavulanic acid, and Tazobactam that block $\beta$-lactamase to protect penicillins from enzymatic destruction.

Vancomycin

A glycopeptide that binds D-Ala-D-Ala to block cell wall synthesis; treats MRSA and C. difficile (PO form) but can cause Red man syndrome, nephrotoxicity, and ototoxicity.

Fluoroquinolones

Inhibit DNA gyrase (topo II) and topoisomerase IV to block DNA replication; examples include Ciprofloxacin, Levofloxacin, and Moxifloxacin.

Fluoroquinolones Adverse Effects

Notable for tendinopathy or rupture, CNS effects (confusion, seizures), photosensitivity, QT prolongation, and dysglycemia.

Metronidazole (Flagyl)

Forms free radicals leading to DNA strand breaks; used for anaerobes and C. difficile; known for a metallic taste and disulfiram-like reaction with alcohol.

Sulfamethoxazole/Trimethoprim (Bactrim)

Causes sequential blockade of folate synthesis (DHPS and DHFR); used for CA-MRSA and P. jirovecii (PCP); can cause SJS/TEN, hyperkalemia, and bone marrow suppression.

Aminoglycosides

Tobramycin and Gentamicin; bind the $30S$ ribosomal subunit to inhibit protein synthesis; require monitoring of IV trough levels due to nephrotoxicity and ototoxicity.

Tetracyclines

Includes Doxycycline; inhibits protein synthesis by binding the $30S$ subunit and blocking aminoacyl-tRNA binding; avoid in pregnancy and children $< 8$ years.

Macrolides

Clarithromycin and Azithromycin; bind the $50S$ ribosomal subunit; used for respiratory infections, pertussis, and Chlamydia.

Clindamycin (Cleocin)

A lincosamide that binds the $50S$ ribosomal subunit; used for anaerobes, Gram positives (including CA-MRSA), and toxin suppression; carries a high risk for C. difficile.