title: Importance of Legionella pneumophila in the etiology of severe community-acquired pneumonia in Santiago, Chile.
abstract: BACKGROUND
  In US and European literature, Legionella pneumophila is reported as an important etiologic agent of severe community-acquired pneumonia (CAP), but in Chile this information is lacking. The aim of this study was to determine the incidence and identify predictors of severe CAP caused by L pneumophila in Santiago, Chile.
  
  
  METHODS
  A multicenter, prospective clinical study lasting 18 months was conducted; it included all adult patients with severe CAP admitted to the ICUs of four hospitals in Santiago. We excluded patients who were immunocompromised, had been hospitalized in the previous 4 weeks, or presented with another disease during their hospitalization. All data for the diagnosis of severe CAP were registered, and urinary antigens for L pneumophila serogroup 1 were determined.
  
  
  RESULTS
  A total of 104 patients with severe CAP were included (mean ± SD age, 58.3 ± 19.3 years; men, 64.4%; APACHE (Acute Physiology and Chronic Health Evaluation) II score, 16.7 ± 6.3; Sepsis-related Organ Failure Assessment score, 6.1 ± 3.2; Pitt Bacteremia Score, 3.4 ± 2.5; Pao2/Fio2, 170.8 ± 87.1). An etiologic agent was identified in 62 patients (59.6%), with the most frequent being Streptococcus pneumoniae (27 patients [26%]) and L pneumophila (nine patients [8.6%]). Logistic regression analysis showed that a plasma sodium level of ≤ 130 mEq/L was an independent predictor for L pneumophila severe CAP (OR, 11.3; 95% CI, 2.5-50.5; P = .002). Global mortality was 26% and 33% for L pneumophila. The Pitt bacteremia score and pneumonia score index were the best predictors of mortality.
  
  
  CONCLUSIONS
  We found that in Santiago, L pneumophila was second to S pneumoniae as the etiologic agent of severe CAP. Severe hyponatremia at admission appears to be an indicator for L pneumophila etiology in severe CAP.
authors.affiliation: Instituto Nacional del Tórax, Santiago, Chile; Clínica Santa María, Santiago, Chile. Electronic address: fearancibia@gmail.com.
authors.forename: Francisco
authors.initials: F
authors.lastname: Arancibia
authors.affiliation: Instituto Nacional del Tórax, Santiago, Chile; School of Medicine, University of Chile, Santiago, Chile.
authors.forename: Claudia P
authors.initials: CP
authors.lastname: Cortes
authors.affiliation: Instituto Nacional del Tórax, Santiago, Chile; Clínica Santa María, Santiago, Chile.
authors.forename: Marcelo
authors.initials: M
authors.lastname: Valdés
authors.affiliation: Hospital Militar de Santiago, Santiago, Chile; Hospital San Borja-Arriarán, Santiago, Chile.
authors.forename: Javier
authors.initials: J
authors.lastname: Cerda
authors.affiliation: Hospital Militar de Santiago, Santiago, Chile.
authors.forename: Antonio
authors.initials: A
authors.lastname: Hernández
authors.affiliation: Instituto Nacional del Tórax, Santiago, Chile.
authors.forename: Luis
authors.initials: L
authors.lastname: Soto
authors.affiliation: Servei de Pneumologia, Institut del Tórax, Hospital Clínic, Institut d'Investigacions Biomediques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomedica En Red-Enfermedades Respiratorias (CibeRes, CB06/06/0028)-Instituto de Salud Carlos III, Madrid, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Torres
mesh_terms: D018806:APACHE; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000652:urine; D002677:Chile / Q000453:epidemiology; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology*; D015897:Comorbidity; D005260:Female; D006801:Humans; D007010:Hyponatremia / Q000453:epidemiology; D016952:Legionella pneumophila / Q000276:immunology / Q000502:physiology*; D007877:Legionnaires' Disease / Q000150:complications*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011008:Pneumococcal Infections / Q000150:complications; D011014:Pneumonia / Q000453:epidemiology / Q000382:microbiology*; D011446:Prospective Studies; D012720:Severity of Illness Index; D013296:Streptococcus pneumoniae / Q000276:immunology / Q000502:physiology; D055815:Young Adult
chemical_list: D000942:Antigens, Bacterial