Reference — Pharmacology
Common Antibiotics Reference
A quick-reference guide to the most commonly used antibiotic classes in clinical nursing practice — with examples, typical clinical uses, and key nursing considerations for each class.
Educational use only. Antibiotic selection, dosing, and duration are provider and pharmacist decisions guided by culture results and clinical findings. Collect cultures before the first antibiotic dose whenever possible. 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 — Quick Reference
| Class | Examples | Typical Uses | Key Nursing Considerations |
|---|---|---|---|
| Penicillins | Amoxicillin, ampicillin, piperacillin-tazobactam (Zosyn), nafcillin, oxacillin | Streptococcal infections, pneumonia, UTI, skin and soft tissue infections, endocarditis, intra-abdominal infections (Zosyn) | Allergy history mandatory before administration; anaphylaxis risk — monitor first 30 min; cross-reactivity with cephalosporins (~1–2%); may cause C. diff and diarrhea |
| Cephalosporins | Cephalexin (1st), cefazolin (1st), cefuroxime (2nd), ceftriaxone (3rd), cefepime (4th) | Surgical prophylaxis (cefazolin), pneumonia (ceftriaxone), UTI, skin infections, meningitis (3rd gen); broader spectrum with higher generations | Ask about penicillin allergy; low cross-reactivity but assess; renal adjustment for higher generations; monitor renal function |
| Macrolides | Azithromycin (Z-pack), clarithromycin, erythromycin | Community-acquired pneumonia (atypicals), pharyngitis (penicillin-allergic), STIs (chlamydia), H. pylori (clarithromycin), atypical respiratory infections | QT prolongation — baseline ECG recommended; give with food to reduce GI side effects; drug interactions via CYP3A4; hepatotoxicity (rare) |
| Fluoroquinolones | Ciprofloxacin, levofloxacin, moxifloxacin | UTI and pyelonephritis (ciprofloxacin), CAP (levofloxacin/moxifloxacin), respiratory tract infections, intra-abdominal, anthrax prophylaxis | QT prolongation; tendon rupture risk (especially Achilles, age >60, corticosteroid use); peripheral neuropathy; CNS effects (confusion); C. diff; antacids/dairy reduce absorption (oral formulations) |
| Tetracyclines | Doxycycline, tetracycline, minocycline | Atypical pneumonia, Lyme disease, Rocky Mountain spotted fever, acne, STIs (chlamydia, gonorrhea), MRSA skin infections (doxycycline) | Avoid in children <8 years old and pregnancy (tooth discoloration, bone growth effects); take with full glass of water; avoid dairy and antacids within 2 hours; photosensitivity — sunscreen required; esophageal ulceration if taken lying down |
| Vancomycin | Vancomycin IV, vancomycin oral (C. diff) | MRSA infections (IV), C. diff colitis (oral), gram-positive infections in penicillin-allergic patients, bacteremia, endocarditis | Trough/AUC-guided dosing — collect trough before 4th dose; nephrotoxicity and ototoxicity monitoring; infuse IV over ≥60 minutes (Red Man Syndrome = flushing/hypotension from rapid infusion — slow rate, not an allergy); renal dose adjustment |
Additional Important Classes
Carbapenems: Imipenem, Meropenem, Ertapenem
Broadest-spectrum beta-lactam antibiotics — reserved for resistant organisms (ESBL, CRE, Pseudomonas). Monitor for seizures (imipenem). Renal adjustment required.
Aminoglycosides: Gentamicin, Tobramycin, Amikacin
Gram-negative coverage; synergistic with beta-lactams for serious infections. Nephrotoxicity and irreversible ototoxicity — peak and trough levels required; monitor hearing and renal function daily.
Metronidazole (Flagyl): Nitroimidazole
Anaerobic bacteria and C. diff (oral). Avoid alcohol during and 48 hours after treatment (disulfiram-like reaction: nausea, flushing, palpitations). Metallic taste is common. Monitor for peripheral neuropathy with prolonged use.
TMP-SMX (Trimethoprim-Sulfamethoxazole / Bactrim)
UTI (uncomplicated), PCP prophylaxis/treatment, MRSA skin infections. Sulfa allergy precaution. Hyperkalemia and renal function monitoring; adequate hydration to prevent crystal nephropathy.
Allergy Considerations
- Penicillin allergy documentation: Document the type of reaction — true allergy (rash, anaphylaxis) vs intolerance (GI upset). True anaphylaxis to penicillin requires avoiding all penicillins; cephalosporin cross-reactivity is ~1–2%.
- Sulfa allergy: Does not cross-react with sulfonylureas or thiazide diuretics — these are different sulfonamide structures
- First dose monitoring: Be present and observe patient for the first 15–30 minutes of any new antibiotic infusion, especially IV antibiotics. Have epinephrine immediately available.
- Anaphylaxis management: Stop infusion, call rapid response, administer epinephrine IM 0.3–0.5 mg (1:1000 concentration) — provider ordered
Culture & Sensitivity — Nurse Responsibilities
- Collect cultures before the first antibiotic dose (except in sepsis/hemodynamic instability — collect simultaneously)
- Blood cultures: two sets from two different peripheral sites; strict aseptic technique; wipe cap with 70% alcohol for 30 seconds; allow to dry
- Notify provider when culture and sensitivity results return — support de-escalation to narrower spectrum when appropriate
- Monitor clinical response to therapy: fever trends, WBC, symptom improvement, and any new or worsening findings
- Communicate lack of response at 48–72 hours for provider reassessment of antibiotic regimen
Related Resources
Standards & sources
Fact-checked Jun 20, 2026This page is written to align with Institute for Safe Medication Practices (ISMP) · FDA prescribing information · The Joint Commission — National Patient Safety Goals. 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 →