Infections in immunocompromised children — viva

Opening (must-hit)

"Fever in an immunocompromised child is an emergency regardless of appearance. I clear the threat gate first — any toxic or shocked child gets the sepsis bundle within the hour. If stable, I take cultures from every line lumen and a peripheral site, confirm the current neutrophil count, and give empiric anti-pseudomonal therapy within 60 minutes. The immune-defect type tells me which organisms to fear." [1] [3]

Branch A — The febrile neutropenic child with a central line

Examiner: The 6-year-old is playing and looks well. The temperature is 38.5 °C. Do you really need to do all this? Candidate: Yes. Up to a third of bacteraemic neutropenic children look well at presentation, and height of fever does not predict serious bacterial infection. The neutrophil compartment that produces the visible signs of infection is absent. I culture every line lumen and a peripheral site, confirm the neutrophil count, give empiric anti-pseudomonal therapy within 60 minutes, and admit. Appearance is not a gate in immunocompromise. [1] [4]

Branch B — The post-HSFT child with hypoxaemia

Examiner: The 4-year-old is three months post-transplant, saturating 88 percent in air, but the chest sounds clear and the radiograph is subtle. Candidate: That is the classic presentation of Pneumocystis jirovecii pneumonia — hypoxaemia disproportionate to the auscultation and radiograph findings, in a T-cell-defective host. I send respiratory samples for immunofluorescence or PCR, start high-dose co-trimoxazole with adjunctive corticosteroids for the hypoxaemia, and escalate to PICU for respiratory support. This is preventable with trimethoprim-sulfamethoxazole prophylaxis, and I would review the prophylaxis adherence. [5]

Branch C — The asplenic child with fever

Examiner: The 3-year-old with sickle cell disease looks well with a temperature of 38.7 °C. The parents wonder if this can wait. Candidate: It cannot. Functional hyposplenism from sickle cell disease means this child cannot clear encapsulated bacteria. Overwhelming post-splenectomy infection can kill within hours from a well-looking starting point. I take blood cultures, give empiric parenteral antibiotic active against encapsulated organisms, and admit. The family should already have vaccination, penicillin prophylaxis, and a written fever action plan — I would review all three at discharge. [6]

Branch D — Persistent fever and the antifungal question

Examiner: The neutropenic child is still febrile on day five despite broad-spectrum therapy. Cultures are negative. What now? Candidate: Persistent fever at day four to seven in a neutropenic child triggers an antifungal reassessment. I send galactomannan and beta-D-glucan, image the chest with contrast CT looking for nodules, halo or air-crescent signs, and review sinuses and skin. If invasive fungal disease is found, voriconazole (with therapeutic drug monitoring) is first-line for aspergillosis; an echinocandin or liposomal amphotericin B is used for invasive candidiasis. [1]

Branch E — The line-lumen culture trap

Examiner: A colleague suggests taking just one blood culture to save the child a peripheral stab. Candidate: I disagree. A single culture misses the line as a source and cannot establish a differential-time-to-positivity. Paired line and peripheral cultures tell me whether the line is implicated. If the line culture turns positive much earlier, or grows the same organism persistently, the line is the source and removal may be required. [1]

Branch F — Gram-positive cover

Examiner: Should you add vancomycin routinely to every febrile-neutropenic regimen? Candidate: No. Routine gram-positive cover does not improve outcomes and broadens toxicity and resistance. I add it for specific indications: line infection, severe mucositis, known colonisation with resistant organisms, haemodynamic instability, or a skin or soft-tissue focus. [1]

Branch G — The safety-net

Examiner: The child defervesces, cultures are negative at 48 hours, and you plan step-down. What do you tell the family? Candidate: I give a specific, rehearsed safety-net: return immediately for any fever, any new pain or rash, any breathing difficulty, or any parental concern the child is worse. I confirm the prophylaxis is in place and understood, and I arrange follow-up with the oncology team. For an asplenic child, I reinforce that any fever is an emergency — present immediately, state the asplenia, expect empiric therapy within the hour. [1] [6]