title: Contribution of a pleural antigen assay (Binax NOW) to the diagnosis of pneumococcal pneumonia.
abstract: OBJECTIVE
  To determine whether the detection of pneumococcal antigen in pleural fluid augments conventional microbiological methods used for the etiologic diagnosis of pneumonia.
  
  
  METHODS
  In this retrospective study, a rapid immunochromatographic test (ICT) [NOW Streptococcus pneumoniae assay; Binax; Scarborough, ME] was performed on pleural fluid samples from 34 patients with pneumonia due to S pneumoniae, 89 patients with effusions of nonpneumococcal origin, and 17 patients with pneumonia of unknown etiology. Data on blood cultures, pleural fluid cultures, and urinary antigen tests were recorded.
  
  
  RESULTS
  The ICT test result was positive in 24 of 34 patients (70.6%) with pneumococcal pneumonia and negative in 83 of 89 patients (93.3%) without pneumococcal pneumonia. The sensitivity of the pleural ICT test was higher than that obtained for blood (37.5%) and pleural fluid cultures (32.3%), but lower than the detection of pneumococcal antigen in urine samples (82.1%). However, three patients with pneumococcal pneumonia and a negative ICT urine test result had a positive pleural fluid antigen detection result test. Previous antibiotic exposure did not influence pneumococcal antigen detection in either pleural fluid or urine specimens. Six additional patients with empyema due to anaerobes (three patients), Streptococcus viridans (two patients), and Enterococcus faecalis (one patient) had false-positive pleural ICT test results. Finally, the ICT assay finding was also positive in 5 of 17 patients (29.4%) with pneumonia without a definite microbiological cause.
  
  
  CONCLUSIONS
  The ICT test performed on pleural fluid samples augments the standard diagnostic methods of blood and pleural fluid cultures, even in the case of prior antibiotic therapy, and enhances the ICT urinary antigen assay.
authors.affiliation: Department of Internal Medicine, Pleural Diseases Unit, Arnau de Vilanova University Hospital, Avda Alcalde Rovira Roure 80, 25198 Lleida, Spain. jporcelp@yahoo.es
authors.forename: José M
authors.initials: JM
authors.lastname: Porcel
authors.forename: Agustín
authors.initials: A
authors.lastname: Ruiz-González
authors.forename: Miquel
authors.initials: M
authors.lastname: Falguera
authors.forename: Antoni
authors.initials: A
authors.lastname: Nogués
authors.forename: Carles
authors.initials: C
authors.lastname: Galindo
authors.forename: Jordi
authors.initials: J
authors.lastname: Carratalá
authors.forename: Aureli
authors.initials: A
authors.lastname: Esquerda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000942:Antigens, Bacterial / Q000032:analysis*; D002845:Chromatography; D017714:Community-Acquired Infections / Q000175:diagnosis / Q000276:immunology; D005260:Female; D006801:Humans; D007118:Immunoassay; D008297:Male; D008875:Middle Aged; D010996:Pleural Effusion / Q000276:immunology*; D011018:Pneumonia, Pneumococcal / Q000175:diagnosis* / Q000276:immunology*; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013296:Streptococcus pneumoniae / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial