Infections in immunocompromised children — formative SAQs

SAQ 1 (10)

A 6-year-old on maintenance chemotherapy for acute lymphoblastic leukaemia presents with a single temperature of 38.6 °C at home. On arrival the child is playing and looks well. There is a central venous catheter in situ; the exit site looks clean. The most recent absolute neutrophil count, two days ago, was 0.3 × 10⁹/L. ^[1]

1. State why this child is an emergency despite appearing well, and the immediate management steps (no invented doses). (4) ^{[1] [4]}
2. Describe the focused bedside examination that is high-yield in this child. (3) ^[1]
3. Outline the principles of empiric therapy, de-escalation, and the safety-net you give the family. (3) ^[1]

Model answer

Why an emergency and immediate steps. A febrile neutropenic child is an emergency regardless of appearance, because the neutrophil compartment that produces the visible signs of infection is absent — up to a third of bacteraemic neutropenic children look well at presentation, and height of fever correlates poorly with serious bacterial infection. Immediate steps are: confirm the current neutrophil count on a fresh sample, take blood cultures from every central-line lumen and a peripheral site, and deliver empiric anti-pseudomonal therapy within 60 minutes of fever recognition, then admit. The agent, dose and route follow the local oncology protocol and are confirmed against current guidelines before administration. ^{[1] [4]}

High-yield bedside examination. The paediatric assessment triangle gates first — any toxic or shocked appearance escalates to the sepsis bundle. The directed examination then covers five high-yield sites: the central-line exit site and tunnel for erythema, swelling, tenderness or discharge; the perianal area for cellulitis or fissure (easy to miss, changes empiric therapy in neutropenia); the oral mucosa for mucositis; the skin for embolic or fungal lesions; and the sinuses and fundi for invasive fungal disease and candida endophthalmitis. Caregiver concern that the child has changed from baseline is taken as data. ^[1]

Empiric therapy, de-escalation and safety-net. Empiric monotherapy with an anti-pseudomonal beta-lactam is standard; gram-positive cover (for example, vancomycin) is added only for line infection, mucositis, known colonisation or instability. Therapy is narrowed to a targeted agent when a focus and organism are identified, and stopped at the protocol-defined interval if the child defervesces with negative cultures. Persistent fever prompts a re-search for source with imaging and fungal biomarkers. The family is given a specific, rehearsed safety-net: return immediately for any fever, any new pain or rash, any breathing difficulty, or any parental concern that the child is worse. ^[1]