Severe community-acquired pneumonia: an integral approach

Severe community-acquired pneumonia represents the most critical manifestation of pneumonia acquired outside the hospital and remains a major cause of intensive care admission and death worldwide. It is frequently complicated by acute respiratory failure, circulatory shock, and multiple organ dysfunction, with mortality commonly exceeding 25-40%. Despite progress in vaccination programmes, microbiological diagnostics, and critical care support, major uncertainties persist regarding early recognition, pathogen identification, antimicrobial selection and duration, management of co-infections, and assessment of treatment response. These challenges are amplified by increasing host heterogeneity and antimicrobial resistance.

Contemporary epidemiological studies consistently demonstrate that mortality in severe community-acquired pneumonia is closely linked to the severity of organ dysfunction rather than to pulmonary involvement alone. In response, the recent international guideline definitions incorporate both respiratory and systemic criteria to standardise identification and guide early triage. However, these frameworks also reveal substantial variability related to host factors that influence clinical presentation, microbiological findings, and outcomes. Advanced age, sex, chronic cardiopulmonary disease, diabetes, frailty, and prior healthcare exposure modify risk, while immunocompromised populations-including transplant recipients, patients with malignancy, individuals receiving immunomodulatory therapies, and people living with Human Immunodeficiency Virus in resource-limited settings-face distinct diagnostic and therapeutic challenges. Accurate microbiological diagnosis remains difficult, with mixed or unidentified infections frequently encountered. Structured respiratory sampling and molecular diagnostic techniques, particularly lower respiratory tract multiplex polymerase chain reaction panels, have improved pathogen detection and support earlier optimisation of antimicrobial therapy. Biomarkers such as procalcitonin and C-reactive protein provide complementary information on disease trajectory and response to treatment, enabling more confident reassessment and earlier discontinuation of antibiotics when aligned with clinical improvement. Severity stratification using combined clinical scores, radiological extent, and laboratory markers refines prognostication and informs treatment intensity. Empiric antimicrobial therapy should be initiated promptly and individualised according to patient-specific risk factors for resistant pathogens, with systematic reassessment within 24-48 h. Adjunctive strategies, including advanced respiratory and haemodynamic support, corticosteroids in selected inflammatory phenotypes, and emerging host-directed therapies such as intravenous immunoglobulins, form part of a personalised management approach.

An integrated, multidisciplinary strategy that links early recognition, diagnostic precision, severity assessment, and personalised therapy offers a coherent pathway to improve outcomes and promote responsible antimicrobial use in severe community-acquired pneumonia.