This Article Full Text Free Full Text (PDF) Free All Versions of this Article: chest.06-1884v1 131/5/1442    most recent Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Add to My Personal Article Archive Download to citation manager Citing Articles Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Porcel, J. M. Articles by Esquerda, A. Search for Related Content PubMed PubMed Citation Articles by Porcel, J. M. Articles by Esquerda, A.

Contribution of a Pleural Antigen Assay (Binax NOW) to the Diagnosis of Pneumococcal Pneumonia^*

^* From the Departments of Internal Medicine (Drs. Ruiz, Falguera, Galindo, and Porcel), Clinical Microbiology (Dr. Nogués), and Laboratory Medicine (Dr. Esquerda), Pleural Diseases Unit, Arnau de Vilanova University Hospital, Institut de Recerca Biomèdica de Lleida, Lleida, Spain; and Infectious Disease Service (Dr. Carratalá), Hospital Universitari de Bellvitge, Barcelona, Spain.

Correspondence to: José M. Porcel, MD, FCCP, Department of Internal Medicine, Arnau de Vilanova University Hospital, Avda Alcalde Rovira Roure 80, 25198 Lleida, Spain; e-mail: jporcelp{at}yahoo.es

Abstract

Study objectives: 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.

Key Words: empyema • immunochromatographic test • pleural effusion • pneumococcal pneumonia