Etiología de la neumonía adquirida en la comunidad en adultos hospitalizados en Santiago, Chile: implicancias para las guías clínicas Background: There are a few studies examining the etiology of community acquired pneumonia (CAP) in Chile. Aim: To evaluate the etiology of CAP in hospitalized adults. Method: We prospectively studied 130 patients (mean age ± SD: 68 ± 18 y.o.; overall hospital mortality: 6.2%), over a 16 month period. Microbiological evaluation included blood and sputum cultures

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... or bacteria; serology for C. pneumoniae, C. psittaci and M. pneumoniae; urine antigen for L. pneumophila; and nasopharyngeal swab for respiratory viruses. Results: Etiology was identified from 64 (49%) patients (two or more pathogens in 6). The most frequent microorganisms were S. pneumoniae (34%), Parainfluenza types 1 to 3 (22%), Influenza A or B (14%), C. pneumoniae (6%), M. pneumoniae (6%), H. influenzae (5%) and S. marcescens (5%). Twenty-five of 27 (93%) respiratory viruses were identified in autumn or winter. Pneumococcal pneumonia patients (19) compared to those infected with respiratory virus (23) were younger (59 ± 18 versus 72 ± 17 y.o.; p = 0.021) and had less comorbidities (47 versus 87%; p = 0.0001). No patients with bacteremia (13 of 121: 11%) died. Conclusions: S. pneumoniae remains the most important pathogen to cover by initial antibiotic therapy; the second most frequent etiological agents were respiratory viruses followed by "atypical pathogens". Recommendations for the management of patients infected with these two last categories of agents should be included in future national guidelines. RESUMEN Fundamento: Hay escasos estudios que examinen la etiología de la neumonía adquirida en la comunidad (NAC) en población adulta chilena. Objetivo: Identificar la etiología de la NAC en adultos inmunocompetentes hospitalizados. Método: Estudiamos, prospectiva y consecutivamente durante 16 meses, a 130 pacientes (edad promedio ± DS: 68 ± 18 años; letalidad en el hospital: 6,2%). La evaluación microbiológica incluyó cultivo de expectoración y hemocultivos para bacterias;