Rapid diagnosis of pneumococcal pneumonia among HIV-infected adults with urine antigen detection

Objectives: Streptococcus pneumoniae is the leading cause of bacterial pneumonia and associated bacteremia during HIV infection. Rapid diagnostic assays may limit inappropriate therapy. Methods: Clinical signs and symptoms and sera and urine were collected prospectively from 70 adults with pneumococcal pneumonia, including 47 with HIV co-infection. Pneumococcal C-polysaccharide antigen was detected in urine using the Binax^® immunochromatographic test (ICT). A systematic review of 24 published studies was conducted. Results: Clinical symptoms, signs, and laboratory parameters except leukocytosis, were similar in HIV-infected and HIV-seronegative pneumonia. The performance of the urine antigen ICT was independent of HIV-status (sensitivity 81%, specificity 98%, positive (PPV) and negative predictive values (NPV) 98%, and 82%, respectively). The sensitivity of sputum Gram's stain was 58% (34/59) with sputum unable to be provided by 16%. The CRP response was identical in HIV-infected (mean ± SD) 133 ± 88 vs. seronegative 135 ± 104 mg/L (p = 0.9). In the systematic review, the ICT performance revealed 74% sensitivity (95% CI 72-77%) and 94% specificity (95% CI 93-95%). Urine antigen testing increases etiologic diagnosis by 23% (range: 10-59%) when testing adults with community acquired pneumonia of unknown etiology. Conclusions: Urinary antigen detection provides a credible rapid diagnostic test for pneumococcal pneumonia regardless of HIV-status. CRP response to acute infection is similar in HIV co-infection and increases diagnostic certainty.