[Assessment of the contribution of the immunochromatographic pneumococcal urinary antigen test to the etiological diagnosis of pneumonia in hospitalized adults].Pathol Biol (Paris). 2010 Apr; 58(2):117-22.PB
AIM OF THE STUDY
To assess the usefulness and prescription practices of the Binax Now Streptococcus pneumoniae urinary antigen test in hospitalized adults.
PATIENTS AND METHODS
The results of the pneumococcal urinary antigen tests (UAT) performed from January 2002 to September 2004 were related to that of microbiological cultures, and in positive patients to radiographic findings and C-reactive protein (CRP) levels. The evolution of the number of prescriptions and positivity rate in 2007 versus 2002-2004 was analyzed.
The pneumococcal UAT was positive in 32 of the 278 patients included from 2002 to 2004 (11.5%). Results were concordant with that of microbiological cultures in 90% of the 247 documented cases. Pneumococcal etiology was considered to be definite in 19 patients (isolation of S. pneumoniae from blood, 17 patients; or pleural fluid, two patients), of whom 15 had a positive UAT (sensitivity: 79%); to be probable in 22 patients (positive UAT, 17 patients and/or isolation of S. pneumoniae from respiratory samples, six patients), and was retained in 39 of the 41 patients (positive predictive value: 93.7%). CRP was greater than 100mg/L in 34 of 39 documented patients and lobar alveolar radiographic opacities observed in 25 of 28 documented patients. In 2007, the dramatic increase in the number of UAT prescriptions and the diversification of prescribing units were associated to a decreased positivity rate (8.1%).
Whereas the pneumococcal UAT clearly increases etiological diagnosis, pneumococcal pneumonia cannot be ruled out if negative. Indications for its use need to be refined to improve the cost-effectiveness of this test.