Acute anaphylaxis after a new antibiotic infusion
A pharmacovigilance case for causality assessment: work out which drug is responsible, grade the reaction's severity and seriousness, and defend a causality category using the WHO-UMC causality assessment.
WHO-UMC causality assessment
- Framework
- WHO-UMC causality assessment
- You decide
- Suspect drug, reaction, severity, seriousness, causality
The case
A 45-year-old man was admitted to hospital with community-acquired pneumonia. His regular medication was amlodipine 5 mg once daily for hypertension. On admission, he was started on intravenous ceftriaxone 2 g once daily and oral azithromycin 500 mg once daily. He had received azithromycin for two doses before the event. Thirty minutes after the first dose of ceftriaxone was infused, he developed sudden onset of generalised pruritus, urticaria, and facial swelling. He then became dyspnoeic and hypotensive with a blood pressure of 82/44 mmHg, heart rate 132 beats per minute, and oxygen saturation 88% on room air. On examination, he had widespread wheeze and a large erythematous rash. He was treated immediately with intramuscular epinephrine, intravenous fluids, hydrocortisone, and chlorphenamine. Serum tryptase measured 90 minutes after symptom onset was elevated. Ceftriaxone and azithromycin were both stopped. He made a complete recovery over the next 24 hours. Rechallenge was not performed. Baseline tryptase performed later was normal.
What you are asked to do
- Identify which of the patient's drugs is the suspect, and say why the others are not.
- Name the reaction and grade its severity.
- Decide whether it is serious by regulatory criteria, which is not the same as severe.
- Assign a causality category under the WHO-UMC causality assessment and justify it from the timeline, the dechallenge and the alternative causes.
- State the management and what should be reported.
The suspect drug and the graded answer are deliberately not on this page: working them out is the exercise.
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A free account opens the trainer: name the suspect drug, grade the reaction and commit to a causality category, then see how your assessment compares and why.
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Educational content for students and clinicians in training. It does not replace professional judgement, local protocols or current prescribing information.