a1 Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
a2 Sanofi-Pasteur Ltd, Toronto, ON, Canada
a3 Centers for Disease Control and Prevention, Atlanta, GA, USA
Streptococcus pneumoniae is a common cause of community-acquired pneumonia (CAP) but existing diagnostic tools have limited sensitivity and specificity. We enrolled adults undergoing chest radiography at three Indian Health Service clinics in the Southwestern United States and collected acute and convalescent serum for measurement of PsaA and PspA titres and urine for pneumococcal antigen detection. Blood and sputum cultures were obtained at the discretion of treating physicians. We compared findings in clinical and radiographic CAP patients to those in controls without CAP. Urine antigen testing showed the largest differential between CAP patients and controls (clinical CAP 13%, radiographic CAP 17%, control groups 2%). Serological results were mixed, with significant differences between CAP patients and controls for some, but not all changes in titre. Based on urine antigen and blood culture results, we estimated that 11% of clinical and 15% of radiographic CAP cases were due to pneumococcus in this population.
(Accepted February 17 2010)
(Online publication March 25 2010)