Usefulness of urinary Streptococcus pneumoniae test for early aetiologic diagnostic of community-acquired pneumonia admitted to a regional hospital (ATHENAS Study)

Abstract number: R2525

de la Rosa R., Fernandez-Rivera J., Marin Y., Serrano C., Romero M.J., Luna A., Ramos A.J., Delgado J.

Objective:Streptococcus pneumoniae is the main cause of community-acquired pneumonia (CAP). The cornerstone for ethiologic diagniostic, sputum culture, may persist negative up to 45% of cases. The aim of the present study was to assess the usefullness of urinary Streptococcus pneumoniae antigen test for early ethiologic diagnostic of CAP in patients who are admitted into a secondary-hospital.

Patients and Methods: A prospective observational study, including the whole 319 CAP diagnosed patients admitted into an Internal Medicine Department between Novemeber 1, 2005 to April 30, 2007, was designed. CAP diagnostic was performed when a new pulmonar infiltrate in Chest X-Ray was observed, along with at least two of the following criteria: fever >38°C, cough, purulent sputum, crackles at chest exploration, peripheral blood leucocites >10,000 cel/mm³). To diagnostic pneumococcal ethiology patients underwent these tests: sputum culture, peripheral blood culture (if patient had fever >38°C) and urinary Streptococcus pneumoniae antigen test (BINAX-NOW pneumonia kit).

Results: Median age of patients analysed was 72 years. During the study were performed sputum culture in 183 patients (57.4%), blood culture in 143 (45%) y urinary Streptococcus pneumoniae antigen test in 287 (90%). 108 cases of pneumococcal-CAP were diagnosed, by means of urinary antigens (95 cases [88%]), sputum culture (23 [21.3%]) y blood culture (9 [8.33%]). Streptococcus pneumoniae was isolated from sputum in twelve patients (52.2%), although urinary test were negative. However, all nine patients who presented with pneumococcal bacteraemia showed a positive urinary antigen test. No statistically differences were found when compared the rate of positivity in urinary test after stratifying the population studied according to severity Fine criteria (p > 0.05; t de Student).

Conclusion: Inclusion of urinary Streptococcus pneumoniae antigen test as a part of early ethiologic study of patients with CAP at admission into hospital is useful. This test allows increase significantly the rate of diagnostics of pneumococal pneumonia in our population, including high severity cases, such as those with bacteraemia.