Not all presentations of Pneumocystis pneumonia (PCP) are managed the same way. When objective gas-exchange measurements place a patient in the moderate-to-severe category, the clinical approach differs substantially from milder disease — including the setting of care, the route of therapy, and the salvage options available if initial treatment is insufficient.
Moderate-to-severe PCP is defined by an alveolar-arterial oxygen gradient greater than 4.7 kPa, together with a PaO₂ below 9.3 kPa, measured at rest breathing room air. Patients meeting these thresholds should receive intravenous therapy initiated in hospital, with the possibility of transitioning to oral therapy once clinical response is established.
For patients in this severity stratum who are not responding to, or are intolerant of, initial therapy, evidence from case series and retrospective studies supports a specific salvage strategy — one that can be used either as monotherapy or in combination. The full regimen, including agent selection, sequencing, and clinical decision points, is in the complete protocol.