[Etiology and prognostics factors of community-acquired pneumonia among adults patients admitted to a regional hospital in Chile]. 
Community-acquired pneumonia (CAP) is a common and serious illness in Chile.  To evaluate the etiology, severity, prognostic factors and blood culture yield of CAP requiring hospitalization in Puerto Montt in Southern, Chile.  All non immunocompromised adults with CAP admitted at Puerto Montt Hospital during one year, were prospectively studied.  Clinical and radiological assessment was done in all patients.  Blood and sputum cultures were obtained and serology for atypical agents was determined.  We studied 200 patients, aged 63+/-19 years (109 males).  The prognostic factors associated with mortality were an age over 65 years, an altered mental status, shock and acute renal failure.  Etiology was demonstrated in 29% of patients.  The most frequent pathogens were Streptococcus pneumoniae (40.7%), Haemophilus influenzae (23.7%) and Chlamydia pneumoniae (16.9%).  Mixed infections were found in 17%.  Fifteen atypical pathogens were identified in 12 patients.  Of these only two received a specific treatment but no one died and their length hospital stay was similar than in the rest of the patients.  Overall, blood cultures were positive in 12.5% of patients, but among alcoholics, 58% were positive.  In only one percent of cases, positive cultures motivated therapeutic changes among clinicians.  Eight percent of S pneumoniae strains were penicillin resistant.  Atypical agents were a common cause of CAP in this group of patients, but their pathogenic role and treatment requirements are debatable.  Focusing blood cultures on specific groups could improve their yield.  The rate of Penicillin resistance for S pneumoniae was.