ICU · infectious-diseases

Pneumonia in the Immunocompromised Patient — Comprehensive ICU Management

Also known as Pneumonia in the immunocompromised host · Opportunistic pneumonia · Pulmonary infiltrates in the cancer patient · Pneumonia in transplant recipients · Pneumonia in haematological malignancy · Invasive pulmonary aspergillosis · Pneumocystis jirovecii pneumonia · CMV pneumonitis

Pneumonia in the immunocompromised host (non-HIV) — haematological malignancy, stem-cell/solid-organ transplant, prolonged steroids, cytotoxic chemotherapy, biologics. The pathogen spectrum is dictated by the SPECIFIC IMMUNE DEFECT: (1) NEUTROPENIA (post-chemo, <0.5 x 10^9/L) - Pseudomonas aeruginosa, other gram-negative bacilli, invasive pulmonary aspergillosis, Candida, mucositis-related viridans streptococci; (2) T-CELL DEFECT (transplant calcineurin inhibitors, fludarabine, alemtuzumab) - Pneumocystis jirovecii (PCP), CMV, Legionella, Nocardia, Cryptococcus, mycobacteria; (3) B-CELL / HUMORAL DEFECT (CLL, myeloma, post-rituximab) - encapsulated bacteria — Streptococcus pneumoniae, Haemophilus influenzae; (4) PROLONGED STEROIDS (20 mg/day prednisone 4 weeks) - PCP, Nocardia, Aspergillus. The intensivist's task: (1) classify the immune defect, (2) get a diagnostic BAL EARLY (galactomannan for Aspergillus, (1-3)-beta-D-glucan for PCP/fungal, CMV PCR, respiratory virus panel, bacterial + fungal + mycobacterial culture), (3) start BROAD EMPIRIC THERAPY — anti-pseudomonal beta-lactam + empiric antifungal (caspofungin for Candida, voriconazole for suspected mould) + ganciclovir if CMV likely + co-trimoxazole if PCP possible + reduce immunosuppression, (4) prefer NIV over intubation (lower VAP/mortality), (5) prophylaxis — co-trimoxazole (PCP), posaconazole (Aspergillus), valganciclovir (CMV). Mortality 20-50% — far higher than immunocompetent CAP. Early appropriate (pathogen-directed) therapy is the single biggest modifiable determinant of survival.