Ferreira, J.Abreu, M.Rodrigues, P.Maia, J.Leuschner, P.Correia, J.2012-08-082012-08-0820122012 Volume 9 Number 2.DOI: 10.5580/2bd6http://hdl.handle.net/10400.16/1273Introduction : Community acquired pneumonia (CAP) is a major cause of hospital admissions and mortality in developed countries. Nevertheless, in about half of the cases a microbial etiology can`t be determined. The need to improve the diagnostic tools of this disease has led to the development of new techniques, such as Streptococcus pneumoniae urinary antigen. Objectives : To analyse the usefulness of the urinary antigen in determining the etiologic diagnosis of pneumonias and its influence in the antibiotherapy modification. Methods : Retrospective analysis of hospitalized patients in 2010 with CAP (n=226) and healthcare associated pneumonia (HCAP) [n=64] diagnosis whose urinary pneumococcal antigen has been analyzed. Results: Median age was significantly greater in HCAP. HCAP patients had more co-morbidities and higher severity scores. Twenty-one patients in the CAP group and 4 patients in the HCAP group had positive pneumococcal antigen. The sensibility of urinary antigen in determining pneumococcal pneumonias was 36% and the specificity 89%. Almost one quarter of the 25 patients with positive urinary antigen had appropriate reductions in antimicrobial spectra, which was not statistically significant when compared with the group with negative urinary antigen. There was a significant relation between a positive urinary antigen and pneumonia severity. Conclusions: Considering its high specificity, the urinary antigen is useful to confirm the presence of pneumococcal pneumonia. Potentially urinary antigen can help to avoid unnecessary treatments in hospitalized patients with CAP.engpneumoniaStreptococcus pneumoniae urinary antigenclinical usefulnessjournal article