ICU · Infectious Diseases
Acute severe community-acquired pneumonia: pneumonia in immunocompromised non-HIV patients
Also known as Pneumonia in transplant recipients · Pneumonia in haematological malignancy · Pneumonia in steroid-treated patients · Opportunistic pneumonia
Pneumonia in non-HIV immunocompromised patients (transplant, haematological malignancy, steroids, biologics) has broader pathogen spectrum and higher mortality than CAP in immunocompetent patients. Organisms depend on type and timing of immunosuppression: early post-transplant (1 month): hospital-acquired (Gram-negative, MRSA). 1-6 months: opportunistic (CMV, PCP, Aspergillus, Nocardia, Legionella). 6 months: community-acquired (same as immunocompetent) + recurrent opportunistic. Management: broad empiric coverage (covers typical + atypical + opportunistic), BAL for diagnosis (send comprehensive panel: bacterial, viral, fungal, mycobacterial), reduce immunosuppression if possible, consider adjunctive therapies (G-CSF for neutropenia, IVIG for humoral). Mortality 20-50%.
Checked against its sources on 9 Oct 2026
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Red flags
- Timing post-transplant determines likely pathogens: <1 month = hospital-acquired, 1-6 months = opportunistic, >6 months = community
- BAL is ESSENTIAL in immunocompromised pneumonia — comprehensive microbiological panel
- CMV pneumonia: treat with ganciclovir — check CMV PCR/load
- Invasive aspergillosis: galactomannan (BAL > serum), CT halo sign, voriconazole
- Neutropenic + new pulmonary infiltrate = invasive mould (Aspergillus, Mucor) until proven otherwise — galactomannan, BAL, CT halo/reverse-halo
- Splenectomised patient with fever = overwhelming post-splenectomy infection (OPSI) — encapsulated organisms, give vaccine + penicillin V prophylaxis, empiric ceftriaxone/vancomycin NOW
- T-cell defect (transplant, high-dose steroids) opens the door to PCP, CMV, Nocardia, Cryptococcus, Toxoplasma — send the full opportunistic panel
- Humoral defect (myeloma, CLL, post-rituximab) = encapsulated bacteria (pneumococcus, H. influenzae, meningococcus) — check IgG, consider IVIG
- Voriconazole interacts with tacrolimus/cyclosporine — adjust CNI dosing and monitor levels; therapeutic drug monitoring is strongly recommended; suspected mucormycosis or voriconazole failure = switch to high-dose liposomal amphotericin B plus surgery
Meet the patient
A 48-year-old man is day 18 after allogeneic stem-cell transplant for AML. His ANC is 0.1 x10 to the 9 per L. He has been febrile (39 degrees) on broad-spectrum meropenem for four days and now develops pleuritic chest pain, haemoptysis and a new oxygen requirement (SpO2 90 percent on room air). CT chest shows several nodules, one with a surrounding halo of ground-glass. Serum galactomannan index is 0.7. He is on fluconazole prophylaxis.[3]
This is the canonical invasive-pulmonary-aspergillosis stem, and it plants the two questions that govern the whole topic: what arm of immunity is missing, and for how long? Neutropenia beyond 10 days with fever refractory to broad-spectrum antibiotics, pleuritic pain and haemoptysis (angioinvasion), and a CT halo sign is invasive mould until proven otherwise — and fluconazole prophylaxis has no anti-mould activity and actively selects for it.[3][7]
References21ShowHide
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- [15]Maertens JA, Raad II, Marr KA, et al. Isavuconazole versus voriconazole for primary treatment of invasive mould disease caused by Aspergillus and other filamentous fungi (SECURE): a phase 3, randomised-controlled, non-inferiority trial. Lancet, 2016.PMID 26684607
- [16]Cornely OA, Alastruey-Izquierdo A, Arenz D, et al. Global guideline for the diagnosis and management of mucormycosis: an initiative of the European Confederation of Medical Mycology in cooperation with the Mycoses Study Group Education and Research Consortium. Lancet Infectious Diseases, 2019.PMID 31699664
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