Chart — Pharmacology
Antibiotic Class Comparison Chart
Side-by-side comparison of major antibiotic classes — with examples, common clinical uses, and key nursing considerations — for rapid clinical reference and NCLEX preparation.
Educational use only. Antibiotic selection is guided by culture results and provider orders. Collect cultures before the first antibiotic dose. Monitor for allergy and adverse effects. Follow institutional protocols. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Antibiotic Classes — Side-by-Side
| Class | Examples | Common Uses | Key Nursing Considerations |
|---|---|---|---|
| Penicillins | Amoxicillin, ampicillin, piperacillin-tazobactam (Zosyn), nafcillin | Streptococcal infections, pneumonia, UTI, skin infections, endocarditis, intra-abdominal (Zosyn) | Check allergy history before each dose; monitor 15–30 min after first dose for anaphylaxis; C. diff and diarrhea risk |
| Cephalosporins | Cephalexin (1st), cefazolin (1st), ceftriaxone (3rd), cefepime (4th) | Surgical prophylaxis (cefazolin), pneumonia (ceftriaxone), UTI, skin infections, meningitis (3rd gen) | Ask about penicillin allergy (low cross-reactivity ~1–2%); renal adjustment for higher generations; monitor renal function |
| Macrolides | Azithromycin (Z-pack), clarithromycin, erythromycin | CAP (atypicals), pharyngitis (penicillin-allergic), STIs (chlamydia), H. pylori | QT prolongation — baseline ECG; give with food; CYP3A4 interactions; hepatotoxicity (rare) |
| Fluoroquinolones | Ciprofloxacin, levofloxacin, moxifloxacin | UTI/pyelonephritis, CAP (levofloxacin), respiratory infections, intra-abdominal | QT prolongation; tendon rupture risk (elderly, corticosteroids); CNS effects; C. diff; antacids reduce oral absorption |
| Tetracyclines | Doxycycline, tetracycline, minocycline | Atypical pneumonia, Lyme disease, RMSF, acne, STIs, MRSA skin infections (doxycycline) | Avoid in children <8 yr and pregnancy; avoid dairy/antacids ±2 hr; photosensitivity — sunscreen; esophageal irritation — take upright with water |
| Vancomycin | Vancomycin IV (MRSA), vancomycin oral (C. diff) | MRSA infections, C. diff colitis (oral), gram-positive infections in penicillin-allergic patients | Trough/AUC-guided dosing; infuse IV over ≥60 min; Red Man Syndrome = flushing/hypotension from rapid infusion (slow rate); nephrotoxicity; ototoxicity |
| Carbapenems | Imipenem-cilastatin, meropenem, ertapenem | Resistant gram-negative organisms (ESBL, Pseudomonas, CRE), serious mixed infections | Broadest spectrum beta-lactam — reserved for resistant organisms; seizure risk (imipenem); renal dose adjustment |
| Metronidazole | Flagyl (IV, oral) | C. diff colitis (oral), anaerobic infections, intra-abdominal infections, bacterial vaginosis, H. pylori | No alcohol during therapy or 48 hr after (disulfiram reaction); metallic taste common; peripheral neuropathy with prolonged use |
Allergy Cross-Reference
| Patient Allergy | Cross-Reactivity Concern | Clinical Approach |
|---|---|---|
| Penicillin (rash) | Cephalosporins: low risk (~1–2%) | Cephalosporins often given; document reaction type; monitor closely |
| Penicillin (anaphylaxis) | Higher concern for cephalosporins; true IgE-mediated risk | Avoid cephalosporins; use alternative class (fluoroquinolone, vancomycin); allergy consultation |
| Sulfa (TMP-SMX) | No clinically significant cross-reactivity with sulfonylureas or thiazides | Avoid TMP-SMX and sulfonamide antibiotics; can usually use other sulfa-containing drugs |
Stewardship Reminders
- Collect cultures before the first antibiotic dose (except in hemodynamically unstable patients — collect simultaneously)
- Monitor clinical response at 48–72 hours — fever trends, WBC, symptom improvement
- Communicate culture and sensitivity results to provider to support de-escalation to narrower-spectrum therapy
- C. diff prevention: use soap and water handwashing (alcohol gel ineffective against C. diff spores)
- Vancomycin therapeutic monitoring: collect trough before 4th dose or per AUC-based protocol
NCLEX Quick Tips
- Cultures BEFORE antibiotics — always a NCLEX priority (unless sepsis emergency)
- Vancomycin Red Man Syndrome: flushing + hypotension during infusion → slow the rate (not an allergic reaction)
- Fluoroquinolones → tendon rupture risk. High risk: elderly, corticosteroid users. Teach patients to report tendon pain.
- Tetracyclines → avoid in children <8 and pregnancy (tooth/bone effects). Photosensitivity — sunscreen required.
- Metronidazole → no alcohol 48 hours after last dose. Disulfiram-like reaction = severe nausea, flushing, palpitations.
- Macrolides → QT prolongation. Baseline ECG if risk factors present.
- C. diff handwashing: soap and water only — alcohol hand gel does NOT kill C. diff spores.
Related Resources
Antibiotic Stewardship for Nurses GuideCulture timing, resistance prevention, monitoring, and nursing responsibilities
Open →Common Antibiotics ReferenceIn-depth reference with additional classes, allergy considerations, and monitoring
Open →Sepsis Recognition and ManagementSepsis bundle: antibiotic urgency, culture timing, and broad-spectrum therapy
Open →Standards & sources
Fact-checked Jun 20, 2026This page is written to align with IDSA / CDC Antibiotic Stewardship Guidelines. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →