Background: Community-acquired pneumonia is a common infection and is associated with high rates of morbidity and mortality. Most patients with CAP[1] are treated empirically.

Objectives: To identify common pathogens causing CAP in hospitalized patients in northern Israel and to evaluate the correlation between etiology and disease severity.

Methods: We conducted a prospective study of patients with CAP hospitalized at HaEmek Medical Center, Afula. We collected demographic, clinical and laboratory data (blood and sputum cultures, serology, pneumococcal urinary antigen test, and respiratory multiplex-polymerase chain reaction from nasopharyngeal swab), and radiologic evaluation was performed.

Results: A total of 126 patients and 24 controls were enrolled. At least one pathogen was identified in 84 cases (66.7%), more than one in 43 patients (34.1%), and no pathogens in 42 (33.3%). Typical bacteria were found in 23 (18.3%), atypical bacteria in 66 (52.4%), and viruses in 42 (33.3%). The number (%) of patients with pathogens isolated was: Chlamydophila pneumoniae 26 (20.6%), Streptococcus pneumoniae 23 (18.3%), Mycoplasma pneumoniae 23 (18.3%), influenza virus A-B 20 (15.9%), Coxiella burnetti 8 (6.3%), and parainfluenza and adenovirus 13 (10.3%) each. A correlation was found only between a high PORT score on admission and S. pneumoniae, although atypical pathogens did not show class predominance.

Conclusions: S. pneumoniae, M. pneumoniae and C. pneumoniae were the most common pathogens isolated, while co-infection was very frequent. PORT score did not predict any of the pathogens involved. The choice of empiric antimicrobial treatment for CAP should be made according to local epidemiologic data.