Background and Aim: Community-acquired pneumonia (CAP) remains one of the leading causes of hospital admissions and a common cause of death. Population-based studies assessing the etiology and incidence of CAP are lacking in developing countries. In this prospective study, we assessed the incidence, etiology, and outcomes of CAP in the Iranian population.
Materials and Methods: This five-year hospital based cross-sectional and descriptive study included 357 patients with CAP, between 18 and 95 years of age. Demographic criteria and clinical data of CAP including fever, cough, sputum, dyspnea, hemoptysis, gastrointestinal symptoms and loss of consciousness were recorded. Laboratory findings and prescribed antibiotics were retrieved from the patients’ records. Results of bronchoalveolar lavage fluid and sputum specimens and also culture results were recorded.

Paired t-test, independent-samples T Test and chi-square were used to examine the relationships among different variables. P<0.05 was considered significant.

Results: The total number of patients in the study was 384 patients, of which 55.2% were male and 44.8% were female (P value = 0.2). The most common underlying disease was community-acquired pneumonia (35.9%). The most common symptom was productive cough, which was observed in 85.2% of the patients. The most common microorganisms isolated from culture were Staphylococcus aureus (9.1%) and Acinetobacter (8.9%). The most commonly used antibiotic in this study was ceftriaxone (43.3). In addition, Acinetobacter species were the most common pathogen in exudative pleural effusion (51.5%). Among the people with higher than normal ESR, 62.2% were male and 37.8% were female, which showed a significant difference (P = 0.03). Out of 89 deaths following pneumonia, 43.8% were under 65 and 56.2% were over 65 years of age, which was significant (P= 0.01).
Conclusion: Considering the high prevalence of Staphylococcus aureus and higher mortality in the elderly and patients with decreased level of consciousness or underlying obstructive pulmonary disease, it is necessary to conduct detailed examinations for sputum culture at the beginning and administer appropriate treatment, based on the identified pathogen as soon as possible in order to reduce drug resistance.