Epidemiology, Etiology and Clinical Outcomes of Community-Acquired Pneumonia in Adults: A Population-Based Study

Background and Objectives: Community-acquired pneumonia remains one of the important reasons for admission to clinical setting and a common cause of death. Population-based studies assessing etiology and incidence are lacking in developing countries. In this prospective study, we assessed the incidence, etiology,and outcome of patients with community-acquired pneumonia in the Iranian population. Materials and Methods: From 2011 to 2016, this hospital based, cross-sectional and descriptive study was conducted on 357 patients with CAP aged from 18 to 95 years. Demographic and clinical data criteria of CAP including fever, cough, sputum, dyspnea, hemoptysis, gastrointestinalsymptoms and loss of consciousness were recorded. Laboratory findingssuch as platelet, WBC count, CRP and ESR values and prescribed antibiotics for treated patients were retrieved from the relevant patient’s files. Results of bronchoalveolar lavage fluids and sputum specimen’s culture medium were also recorded. Results: The most frequent underlying diagnosis is COPD (138; 35.9 %) and heart failure (52; 13.5%) (P-value<0.5). Of 357patients diagnosed with CAP (community-acquired pneumonia), 172 positive sputum or bronchoalveolar lavage (BAL) culture were reported. The most common microorganisms respectively are Staphylococcusaureus (20.34%), Acinetobacter species(19.76%) andStreptococcus pneumoniae(11.62%). In addition, S. aureuswas the single most prevalent organism in patients with hemoptysis and gastrointestinal symptoms (p-value<0.05). Acinetobacter spp.were more prevalent in patients with loss of consciousness and exudative effusion (p-value<0.05). Our data have also revealed that Acinetobacter spp.were the most common pathogen in exudative pleural effusions (51.5%), followed by S. aureus (37.1%)(p-value<0.05). Furthermore, Acinetobacter spp. (21.2%) was the organism causing the highest mortality, followed by S.aureus (14.2%). Among the investigated laboratory variables, thrombocytosis, thrombocytopenia, leukocytosis andleukopenia were correlated with death. Conclusion: This study has revealed interesting epidemiological aspects of CAP disease. Greater attempt should be made to promote the ability of laboratories for identification of microbial pathogens causing CAP.