The antibiotic that won't stop — antimicrobial stewardship structured encounter

Station status

This is one MedVellum formative structured clinical encounter. The scoring, prompts and performance descriptions are educational feedback tools. They are not an official college station, timing, mark allocation, pass score or reproduced examination format. The encounter assesses empiric-to-targeted antimicrobial selection, developmental dosing, therapeutic drug monitoring, de-escalation, IV-to-oral switch, penicillin allergy delabeling, and duration review. [1] [13]

Candidate instructions

You are the paediatric registrar on the ward. Emma has been on broad intravenous antibiotics for 4 days for a complicated skin and soft tissue infection. Her blood cultures at 48 hours grew Streptococcus pyogenes sensitive to penicillin. The team has not reviewed the prescription since admission. Her mother wants to know when Emma can go home. Review the antimicrobial plan: de-escalate, switch to oral, assess the penicillin allergy label on her chart, and set a clear duration and stop date. Speak directly to Emma and her mother. Do not perform painful manoeuvres on the actor; say what you would assess or do instead. [1] [13]

Room setup and observable starting state

The encounter. Emma is 6 years old and 20 kg. She has been afebrile for 36 hours, is eating and drinking, and is playing in the bed. Her intravenous cannula is in situ. Her drug chart shows intravenous flucloxacillin and clindamycin, both continuing since admission, plus a documented penicillin allergy from infancy described as "rash." [1] [13]

What is visible before touch. Emma looks well and is interacting. These observations indicate clinical improvement. The candidate should recognise that the prescription has not been reviewed since the cultures returned, that de-escalation and oral switch are overdue, and that the penicillin allergy label warrants assessment. The stewardship opportunity is immediate. [1] [13]

Simulation safety. Emma remains in bed. Cards or the assessor supply observations, culture results, and drug chart data. No painful or distressing manoeuvre is performed on the actor. [13]

Actor cues

Child actor

• When the candidate uses Emma's name and engages her, look up and smile briefly. [1]

Caregiver actor

• Begin with: "She's much better today. Can we go home soon? She hates the drip." If asked about the original penicillin allergy reaction, answer: "She had a rash when she was a baby, I think after some amoxicillin. They just told me to avoid penicillin. She's never had a bad reaction since." [10] [11]

Assessor cues and clinical data

Give each finding only when the candidate reaches that step or asks for it. Interpret the drug chart using the current local formulary and allergy guidance. The Royal Children's Hospital Melbourne Antibiotic guidelines are one example pathway; they are not a universal rule. [1] [13]

The IDSA/SHEA stewardship guidelines support the daily review and de-escalation steps. This encounter gives no specific dose; the candidate should follow the active local formulary, use age- and weight-appropriate dosing, and state the plan clearly. [1]

Stewardship cue within the same encounter

Once the candidate has reviewed the prescription and the culture result, say: "The culture has been back for 48 hours. What changes would you make?" This is not a second case. The candidate should de-escalate from flucloxacillin and clindamycin to a targeted penicillin (or a suitable alternative if the allergy cannot be resolved), switch to oral, and set a stop date. [1] [13]

Expected candidate sequence

1. Review and de-escalate. Note that cultures returned 48 hours ago showing S. pyogenes sensitive to penicillin. Stop clindamycin (no longer needed) and narrow from flucloxacillin to benzylpenicillin or phenoxymethylpenicillin once the allergy is resolved. State why continued broad empiric therapy without review is a stewardship failure. [1]
2. Assess the penicillin allergy. Take a structured history: the original reaction was a rash in infancy with no features of IgE-mediated allergy, and there has been no reaction since. This is low-risk. Explain the plan for risk-stratified oral challenge and delabeling, citing the PALACE trial evidence that direct oral challenge is safe in the majority of low-risk patients. [10] [11]
3. Switch to oral. Emma meets the criteria: improving, afebrile for 36 hours, eating and drinking, and an oral agent with good bioavailability is available once the allergy is resolved. Explain the pharmacological rationale for oral switch and the benefits: shorter stay, no line, earlier return to normal activity. [1] [13]
4. Set the duration. Prescribe the shortest evidence-based course for cellulitis (typically 5 to 7 days total, counting IV and oral). Document the indication, the start, the stop date, and the review point. Explain the audit-and-feedback safeguard. [1]

MedVellum formative marking domains

This educational rubric has 10 domains scored 0–3, giving a MedVellum formative total of 30. Score 0 for omitted or unsafe, 1 for named but incomplete, 2 for clear and safe, and 3 for integrated, prioritised and reassessed. This is not an official board mark or pass standard. Feedback should identify the first unsafe step, not only the total. [1] [13]

Critical fails

Any item below overrides a reassuring formative total because it creates immediate avoidable risk. [1] [13]

• Failing to de-escalate when the organism and sensitivities are known.
• Continuing broad empiric therapy without a documented indication or review date.
• Accepting the penicillin allergy label without assessment and driving broader, more toxic therapy.
• Prescribing a long default duration without a documented stop date or evidence-based endpoint.

Examiner prompts

Use as few neutral prompts as possible. A prompted behaviour can receive no more than 2/3 in the affected MedVellum formative domain. This is an educational feedback convention, not an official examination rule. [1] [13]

1. "The cultures have been back for 48 hours. What would you change?"
2. "Tell me about the penicillin allergy on her chart."
3. "Can she go home on oral antibiotics?"
4. "How long should the total course be?"

Model performance

Emma has been on broad empiric therapy for four days, but her cultures returned at 48 hours showing Streptococcus pyogenes sensitive to penicillin — so I would de-escalate immediately by stopping clindamycin and narrowing from flucloxacillin to benzylpenicillin or oral penicillin V. The penicillin allergy label is from an infant rash with no features of IgE-mediated allergy and no subsequent reactions, which is low-risk: I would take a structured history and arrange risk-stratified oral challenge to delabel her, as the PALACE trial confirmed this is safe. She is afebrile for 36 hours, eating and drinking, and clinically improved, so she meets the criteria for IV-to-oral switch to oral penicillin V. I would prescribe the shortest evidence-based total course for cellulitis with a documented stop date, explain to her mother that she can complete therapy at home, and feed the de-escalation back through the stewardship audit process. [1] [10] [11] [13]

Disposition and safety-net standard for this encounter

Emma can complete therapy at home on oral antibiotics once the switch is made and the allergy is resolved. Her mother is given a written plan with the drug, dose, duration, stop date, and the specific signs that should prompt return — spreading redness, fever, increasing pain, or systemic illness. Handover includes the de-escalation decision, the allergy delabeling outcome, and the ownership of any pending results. [1] [13]