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]

SAQ 2 (10)

A 3-year-old with sickle cell disease is brought to the emergency department with a single temperature of 38.7 °C. The child looks well and is interactive. The parents are unsure what to do when the child has a fever. [5]

1. Explain why this child is an emergency and state the immediate management (no invented doses). (4) [5]
2. Describe the three-pillar infection-prevention pathway that should already be in place for this child. (4) [5]
3. Contrast this child's risk with that of a child with chemotherapy-induced neutropenia. (2) [1] [5]

Model answer

Why an emergency and immediate management. Sickle cell disease produces functional hyposplenism from early infancy, so this child cannot clear encapsulated bacteria — pneumococcus, Haemophilus influenzae type b, meningococcus — from the bloodstream. Overwhelming post-splenectomy infection can present with a well-looking child who progresses to septic shock and death within hours. Immediate management is blood cultures, empiric parenteral antibiotic active against encapsulated organisms, and admission for observation; the agent and dose follow local protocol and are confirmed against current guidelines before administration. Waiting or outpatient management is unsafe. [5]

Three-pillar prevention pathway. The pathway has three pillars. First, age-appropriate plus additional vaccination against pneumococcus, meningococcus (including serogroup B), and Haemophilus influenzae type b, on top of the routine schedule. Second, penicillin prophylaxis, especially in children under five years. Third, a written, rehearsed fever action plan that tells the family to present immediately for any fever, to state the asplenia, and to expect empiric therapy within the hour. Any single measure alone is insufficient. [5]

Contrast with chemotherapy-induced neutropenia. The sickle-cell child's defect is loss of splenic clearance of encapsulated bacteria — the risk is fulminant bacteraemia from a defined organism group, prevented by vaccination, prophylaxis and a fever action plan. The chemotherapy child's defect is neutropenia — the risk is gram-negative bacteraemia (especially Pseudomonas) and invasive fungal disease, prevented by prompt empiric therapy and (for Pneumocystis) trimethoprim-sulfamethoxazole prophylaxis. Both are emergencies on first fever, but the organism spectrum, the prophylaxis and the empiric therapy differ. [1] [5]