Cellulitis in a penicillin-allergic patient with renal impairment
Write a prescription for lower limb cellulitis and have every line marked: drug choice, dose, route, frequency and duration, checked against the patient's allergies, current medicines, renal function and the interaction database, with each error explained.
medium8 scoring rulesrenal impairment
- Patient
- 65 years, female, 70 kg
- Diagnosis
- Lower limb cellulitis
- Renal function
- eGFR 25 mL/min/1.73m²
- Allergies
- penicillin
The scenario
Presenting complaint: A 65-year-old woman presents with a two-day history of increasing redness, swelling, and pain in the right lower leg. She has a small ulcer on the shin that she noted after scraping it on a bench. Over the past 24 hours, the erythema has expanded and she feels feverish, but has no nausea or vomiting. She has no other symptoms.
Examination findings: Temperature 38.1 °C, pulse 96/min, blood pressure 134/82 mmHg, respiratory rate 18/min, oxygen saturation 96% on air. On the right lower leg, there is an area of well-demarcated, warm, tender erythema covering the shin and extending from the ankle to just below the knee. No purulence, no fluctuance, no crepitus. Peripheral pulses are palpable and sensation is intact. The rest of the examination is unremarkable.
Investigations: White cell count 14.5 x 10^9/L with neutrophilia, C-reactive protein 96 mg/L. Blood cultures are pending. Renal function: serum creatinine 2.0 mg/dL, eGFR 25 mL/min/1.73 m^2. Liver function tests are normal. Glucose is normal.
Allergies: The patient reports a documented history of anaphylaxis to penicillin, with angio-oedema and hypotension after a dose of oral penicillin in the past. She has been advised to avoid all penicillins and cephalosporins.
Current medicines: Amlodipine 5 mg once daily for hypertension, and levothyroxine 75 micrograms once daily for hypothyroidism.
Diagnosis: Lower limb cellulitis.
Task: Prescribe an appropriate oral antibiotic for this patient. Consider the allergy and the renal impairment in your choice and dosing.
What gets marked
- Whether you chose an indicated drug, and whether you avoided the contraindicated ones.
- Dose, route, frequency and duration against the range for this patient.
- Renal and hepatic dose adjustment where this patient's numbers demand it.
- Allergy cross-reactivity and interactions with the medicines already on the chart.
- The instructions and monitoring you write, not only the drug you pick.
8 scoring rules apply to this scenario. A single critical error fails the attempt whatever the score.
Log in to prescribe for "Cellulitis in a penicillin-allergic patient with renal impairment"
A free account opens the prescription pad: search the formulary, write the chart, and have it marked line by line by the safety engine.
Taught in
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Educational content for students and clinicians in training. It does not replace professional judgement, local protocols or current prescribing information.