Pneumonia Pathogens' Virulence Factors, Patient Inflammatory Markers, and Their Associations With Outcomes

The study aims to evaluate pneumonia symptoms using physical examinations, radiological and laboratory tests, and prognostic scales such as the Pneumonia Severity Index (PSI) and CURB65. These methods will be combined with the assessment of biomarkers and inflammatory cytokines to enhance clinical decision-making and predict adverse outcomes. Procalcitonin (PCT) levels will help guide the initiation and duration of antibiotic therapy, while variations in treatment may be based on initial levels of inflammatory biomarkers. A notable focus is placed on the CD64 marker, which can increase significantly under the influence of pro-inflammatory cytokines (IL-6, G-CSF) within hours and return to baseline as the infection subsides. Microbiological testing will be performed selectively, particularly when results could affect antimicrobial therapy choices. Sputum microscopy is planned before antibiotic prescription, with only high-quality samples being considered. Poor-quality sputum will not be further tested. Invasive diagnostic methods will be used only as specified by pneumonia treatment protocols. Bronchoscopy, including bronchoalveolar lavage (BAL), is reserved for severe pneumonia cases under specific conditions, such as failure to expectorate sputum, multiple Gram-negative or fungal isolates, or poor treatment response. Radiological diagnostics will include chest X-rays in anteroposterior and lateral views, as infiltrates in certain lung segments may be missed on single views. Early radiographic findings may reveal only subtle changes in the lung pattern, so follow-up imaging is planned to ensure an accurate diagnosis. The study will be conducted exclusively in specialized hospital units to maintain patient safety. The collected data will allow for the analysis of relationships between pathogens, their virulence, immune responses, and disease outcomes.