Evaluation of the Binax NOW Streptococcus pneumoniae urinary antigen assay in intensive care patients hospitalized for pneumonia

Objective: To evaluate the diagnostic performance of Binax Now S. pneumoniae urinary antigen rapid immunochromatographic membrane test (ICT) for patients with suspicion of community-acquired pneumonia hospitalized in intensive care and to assess the impact of prior antibiotics on its diagnostic performance. Design and setting: Retrospective study in a medicosurgical ICU in a 700-bed general hospital. Patients: Charts of patients with ICT performed (result blinded) were reviewed between May 2002 and July 2004. ICT has been performed in 140 of the 1,006 patients hospitalized in the unit; two-thirds had received antibiotics prior to admission. Measurements and results: Diagnosis of pneumonia was made according to usual criteria. All patients had at least one microbiological test. Pneumonia diagnosis confirmed in 108 patients including 32 pneumococcal. ICT was positive in 23 of 32 patients with pneumococcal pneumonia, in 11 of 108 without, and in none of the 32 patients without pneumonia, resulting in sensitivity, specificity, and positive and negative predictive values of, respectively: 72%, 90%, 68% and 92%. Positive likelihood ratios were comparable among patients with or without prior antibiotics (respectively 6 and 12 for 7 in the overall population). Conclusions: This first clinical evaluation of ICT in intensive care patients hospitalized for suspicion of community-acquired pneumonia, demonstrated performance in accordance with published data even in the case of prior antibiotics. Its clinical interest and impact on antibiotics policy remain to be refined.