Persistence of Streptococcus pneumoniae urinary antigen excretion after pneumococcal pneumonia

The aim of this study was to determine the duration of Streptoccocus pneumoniae antigen excretion in urine after pneumococcal pneumonia. Urinary antigen detection remained positive in nonconcentrated urine in 18 (52.9%) of the 34 patients in the first month after pneumonia diagnosis. In 12 of these positive cases, the test was still positive in the second month, in six patients after 4 months, and in two cases 6 months after the diagnosis of pneumonia. Using concentrated urine, antigenuria remained positive in all patients for at least 3 months, with antigen detected in three cases more than one year later. We did not observe a relation between age, gender, immunosuppression, underlying diseases, pneumonia severity, positive blood culture, or X-ray presentation and longer-term antigenuria excretion. However, the small number of patients evaluated is a limitation for statistical analysis. In order to correctly analyse a positive urinary antigen test result in patients with pneumonia, it is necessary to know which patients have recently had a previous episode of pneumonia.