antimicrobial therapy

What is selective toxicity?

Ability of antimicrobials to kill bacteria without harming host (via disrupting cell walls, enzymes, or protein synthesis).

Broad vs. Narrow spectrum antibiotics?

Broad = active against many organisms (↑ superinfection risk). Narrow = active against few organisms (preferred when pathogen known).

Bactericidal vs. Bacteriostatic?

Bactericidal = directly lethal. Bacteriostatic = slows bacterial growth.

What is a superinfection?

New infection during antibiotic therapy due to loss of normal flora (e.g., C. diff).

What are nosocomial infections?

Hospital-acquired infections, often resistant due to heavy antibiotic use.

Penicillins - mechanism of action?

Inhibit cell wall synthesis → bacteria rupture & die.

Penicillins - adverse effects?

Allergic reactions (rash → anaphylaxis), pain at injection. Cross-sensitivity with cephalosporins.

Penicillins - nursing considerations?

Give on empty stomach with water, monitor renal, full course required, do not mix with aminoglycosides.

Examples of Penicillins?

PCN G (narrow), Amoxicillin/Ampicillin (broad), Augmentin, Zosyn (with beta-lactamase inhibitors).

What is MRSA?

Methicillin-resistant Staph. aureus; resistant to all PCNs and most cephalosporins.

Cephalosporins - prototype & action?

Cefalexin (Keflex); disrupt cell wall synthesis causing death.

Cephalosporins - trends by generation?

↑ G- coverage, ↑ resistance to beta-lactamase, ↑ CSF penetration.

Cephalosporins - adverse effects?

Allergic reactions, bleeding, pain at injection site.

Cephalosporins - nursing considerations?

Monitor renal function, full course required.

Vancomycin - uses?

MRSA, C. diff (if Flagyl fails), PCN allergy.

Vancomycin - adverse effects?

Nephrotoxicity, ototoxicity, thrombophlebitis, Red Man Syndrome (if infused too fast).

Vancomycin - nursing considerations?

Administer IV slowly, monitor peak & trough levels.

Carbapenems - prototype & use?

Imipenem (Primaxin); very broad spectrum, effective vs. G+/- & anaerobes, good for mixed infections.

Carbapenems - adverse effects?

N/V/D, hypersensitivity.

Carbapenems - nursing considerations?

Reduce dose if renal impairment.

Aminoglycosides - prototype & action?

Gentamycin; inhibits protein synthesis, bactericidal.

Aminoglycosides - uses?

Serious G- infections (E. coli, Klebsiella, Pseudomonas).

Aminoglycosides - adverse effects?

Nephrotoxicity, ototoxicity, neuromuscular blockade.

Aminoglycosides - nursing considerations?

Monitor renal, monitor peak & trough levels.

Fluoroquinolones - prototype & action?

Ciprofloxacin; inhibits bacterial DNA replication/enzymes.

Fluoroquinolones - uses?

UTIs, respiratory infections, GI infections (E. coli, Klebsiella).

Fluoroquinolones - adverse effects?

GI upset, phototoxicity, tendon rupture, ↑ risk of C. diff, confusion in older adults.

Fluoroquinolones - nursing considerations?

Avoid milk/Ca/iron with PO dose, monitor for tendon pain.

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What causes C. diff colitis?

Broad-spectrum antibiotics → watery, foul-smelling diarrhea.

Treatment for C. diff colitis?

Metronidazole (Flagyl) or Vancomycin.

When is combination antibiotic therapy used?

Severe unknown infections, TB, mixed infections.

When are prophylactic antibiotics appropriate?

Certain surgeries, bacterial endocarditis risk, severe neutropenia.