Chest
Volume 131, Issue 3, March 2007, Pages 779-787
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Original Research: Infections
Etiology of Community-Acquired Pneumonia in Hospitalized Patients in Chile: The Increasing Prevalence of Respiratory Viruses Among Classic Pathogens

https://doi.org/10.1378/chest.06-1800Get rights and content

Abstract

Background and study objectives:The range and relative impact of microbial pathogens, particularly viral pathogens, as a cause of community-acquired pneumonia (CAP) in hospitalized adults has not received much attention. The aim of this study was to determine the microbial etiology of CAP in adults and to identify the risk factors for various specific pathogens.

Methods:We prospectively studied 176 patients (mean [± SD] age, 65.8 ± 18.5 years) who had hospitalized for CAP to identify the microbial etiology. For each patient, sputum and blood cultures were obtained as well as serology testing forMycoplasma pneumoniaeandChlamydophila pneumoniae, urinary antigen testing forLegionella pneumophilaandStreptococcus pneumoniae, and a nasopharyngeal swab for seven respiratory viruses.

Results:Microbial etiology was determined in 98 patients (55%).S pneumoniae(49 of 98 patients; 50%) and respiratory viruses (32%) were the most frequently isolated pathogen groups. Pneumococcal pneumonia was associated with tobacco smoking of > 10 pack-years (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.2 to 5.4; p = 0.01). Respiratory viruses were isolated more often in fall or winter (28%; p = 0.011), and as an exclusive etiology tended to be isolated in patients ≥ 65 years of age (20%; p = 0.07). Viral CAP was associated with antimicrobial therapy prior to hospital admission (OR, 4.5; 95% CI, 1.4 to 14.6).

Conclusions: S pneumoniaeremains the most frequent pathogen in adults with CAP and should be covered with empirical antimicrobial treatment. Viruses were the second most common etiologic agent and should be tested for, especially in fall or winter, both in young and elderly patients who are hospitalized with CAP.

Section snippets

Materials and Methods

A prospective cohort study of consecutive patients admitted to the hospital with CAP was conducted between February 27, 2003, and April 15, 2005, at a 520-bed university-affiliated teaching hospital in Chile. The study received institutional review board approval, and informed consent was obtained from all patients. Subjects were included if they were not immunocompromised, were ≥ 16 years of age, and had radiographically confirmed pneumonia requiring hospitalization. CAP was defined as the

Patient Characteristics

One hundred seventy-six patients (91 men and 85 women; mean age, 65.8 ± 18.5 years; range, 17 to 101 years) were studied. The principal clinical characteristics and chest radiograph findings are summarized inTable 1. The mean duration of clinical symptoms before hospital admission was 7.1 ± 5.7 days. Thirty percent of patients had received an antibiotic prior to hospital admission, and 20% were admitted to the ICU.

Diagnostic Yield of Applied Techniques

The number of samples collected and their yield are summarized inTable 2. For

Discussion

This study is the first to document the relative importance of various pathogens in causing CAP in hospitalized patients in Chile, a developing country. The main results were as follows:S pneumoniaewas the most frequent pathogen found followed by respiratory viruses; viruses were more common in elderly patients, and were isolated mainly in the fall or winter; and viral CAP patients had significant mortality.

The etiology was found in 55% of cases, and this figure is similar to those from some

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    This research was supported by a grant from Dirección de Investigación de la P. Universidad Católica de Chile (DIPUC 2003/10E) and by investigation grants from Sociedad Chilena de Enfermedades Respiratorias (2002 and 2004).

    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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