Pneumocystis jirovecii Pneumonia in HIV-negative Patients, a Frequently Overlooked Problem. Case Series from a Large Italian Center.

BACKGROUND AND OBJECTIVES: Pneumocystis jirovecii pneumonia (PCP) still has substantial morbidity and mortality. For non-HIV patients, course of infection is severe, and management guidelines relatively recent. We collected all PCP cases (EORTC criteria) diagnosed in HIV-negative adult inpatients in 2019-2020 at our Center in northern Italy.

RESULTS: Of twenty cases, 9/20 had microbiologic evidence of probable (RT-PCR) and 11/20 of proven (immunofluorescence) PCP on respiratory specimens. Half were female, median age was 71.5 years; 14/20 had hematologic malignancies, 5 had autoimmune/hyperinflammatory disorders, 1 a solid tumor. RT-PCR cycle threshold (Ct) was 24-37 for broncho-alveolar lavage (BAL), 32-39 for sputum; Ct was 24-33 on BAL proven cases. 4/20 received additional diagnoses on BAL. At PCP diagnosis, all patients were not on anti-Pneumocystis prophylaxis. We retrospectively assessed prophylaxis indications: 9/20 patients had a main indication, 5/9 due to prednisone treatment ≥ 20 mg (or equivalents) for ≥4 weeks. All patients underwent antimicrobial treatment according to guidelines; 18/20 with concomitant corticosteroids. 4/20 patients died within 28 days from diagnosis.

CONCLUSION: Despite appropriate treatment, PCP is still associated to high mortality (20%) among non-HIV patients. Strict adherence to prophylaxis guidelines, awareness of grey areas and prompt diagnosis can help manage this frequently overlooked infection.