High-Yield Antibiotic Flashcards – Part 3: Mechanisms, Resistance & Nursing Safety

What is the primary mechanism of action for beta-lactam antibiotics (penicillins, cephalosporins, carbapenems)?

They inhibit bacterial cell-wall synthesis by binding to penicillin-binding proteins, causing lysis and death.

What is the mechanism of action for aminoglycosides?

They inhibit bacterial protein synthesis by binding to the 30S ribosomal subunit, causing defective proteins and cell death.

What is the mechanism of action for tetracyclines?

They inhibit bacterial protein synthesis by preventing tRNA from binding to the ribosome; bacteriostatic.

What is the mechanism of action for macrolides (erythromycin, azithromycin)?

They bind to the 50S ribosomal subunit, inhibiting protein synthesis; usually bacteriostatic.

What is the mechanism of action for sulfonamides and trimethoprim?

They block bacterial folic-acid synthesis at sequential steps, preventing DNA replication.

What is the mechanism of action for fluoroquinolones?

They inhibit bacterial DNA gyrase (topoisomerase II) and topoisomerase IV, blocking DNA replication.

What is the mechanism of action for vancomycin?

It binds to bacterial cell-wall precursors (D-Ala-D-Ala), preventing cell-wall synthesis in gram-positive bacteria.

What is the mechanism of action for clindamycin?

It binds to the 50S ribosomal subunit, inhibiting protein synthesis—particularly effective against anaerobes.

What are the three main mechanisms bacteria use to develop antibiotic resistance?

(1) Enzymatic drug inactivation, (2) altered drug targets, and (3) increased drug efflux.

What bacterial gene makes microbes resistant to nearly all antibiotics?

The NDM-1 (New Delhi metallo-beta-lactamase-1) gene.

How do bacteria commonly acquire new resistance traits from other bacteria?

Through conjugation, where plasmid DNA carrying resistance genes is transferred between bacteria.

Why do broad-spectrum antibiotics promote resistance more than narrow-spectrum ones?

They eliminate more normal flora, creating selective pressure that favors resistant organisms.

What is the Minimum Inhibitory Concentration (MIC)?

The lowest antibiotic concentration that completely suppresses visible bacterial growth.

What is the Minimum Bactericidal Concentration (MBC)?

The antibiotic concentration that reduces bacterial colonies by 99.9%.

How can hospitals delay the emergence of antibiotic resistance?

(1) Prevent infections, (2) diagnose/treat effectively, (3) use antimicrobials wisely, and (4) prevent patient-to-patient spread.

What is a major external contributor to antibiotic resistance worldwide?

Routine antibiotic use in livestock feed to promote growth.

Why is host immunity important for antibiotic success?

The immune system and phagocytes help clear bacteria that antibiotics only suppress.

When are antibiotic combinations appropriate?

For severe initial infections, polymicrobial infections, tuberculosis, or when synergy enhances effectiveness.

What are universal nursing teaching points for antibiotics?

Finish the full course, report rash or diarrhea, avoid alcohol when instructed, take with/without food as directed, and use backup contraception.

What is the nurse’s most critical responsibility before administering any antibiotic?

Assess for allergies, verify the correct drug, dose, indication, and review labs or cultures before giving.