This multicentric, prospective study aims at:

evaluating the prevalence, etiology, characteristics, and 1one-year outcomes of immunocompromised patients hospitalized for Community-Acquired Pneumonia (CAP); conducting biochemical, microbiological and genetic analysis on collected samples.

Primary endpoint:

Collection of in- hospitalisation mortality for all causes in immunocompromised patients with CAP enrolled.

Secondary endpoints:

Collection of data on admission and during hospitalisation to evaluate clinical response to empirical treatments (including antibiotic therapy) related to severity of disease and microbiological etiology.

Prevalence of cardiovascular events and all-cause mortality during hospitalization or after discharge.

Biochemical, microbiological and genetic analysis on collected samples.

Inclusion Criteria:

Hospitalized patients with a confirmed diagnosis of Community-Acquired Pneumonia (CAP) characterized by at least one of the following risk factors for immunosuppression:

• AIDS,
• Aplastic anemia;
• Asplenia;
• Hematologic malignancy (e.g., lymphoma/acute or chronic myeloid leukemia/multiple myeloma);
• Chemotherapy within the last 3 months;
• Neutropenia defined as a white blood cell count less than 500/dL on a complete blood count;
• Use of biologics (including trastuzumab and therapy for autoimmune diseases (e.g., anti-TNF α), prescribed within the last 6 months before hospital admission;
• Solid organ transplant;
• Bone marrow transplant;
• Chronic oral steroid use (>10 mg/day prednisone or equivalent ≥3 months before accessing the ED, or cumulative dose > 600 mg prednisone);
• Use of corticosteroid therapy with a dose ≥ 20 mg prednisone or equivalent ≥14 days or cumulative dose > 600 mg prednisone;
• Active malignancy;
• Malignancy within one year of pneumonia (excluding patients with localized skin cancer or early-stage malignancy);
• Lung malignancy with neutropenia/chemotherapy;
• Other solid malignancy with neutropenia/chemotherapy;
• Other immunodeficiency (including congenital/genetic immunosuppression and immunosuppressive therapy secondary to hematologic malignancy or solid malignancy);
• Primary immunodeficiency.

Exclusion Criteria:

• None

Immunosuppressed patients with Community-Acquired Pneumonia will be enrolled during hospitalization in Italian Pneumology, Infectious Diseases and Emergency Departments selected on their specific experteeze and know-how. Upon discharge, patients will be followed up at 30 days, 3 months, 6 months and 12 months after discharge.