Point-of-care urinary pneumococcal antigen test in the emergency department for community acquired pneumonia

Streptococcus pneumoniae is the most common cause of community-acquired pneumonia (CAP). Early diagnosis would allow more directed therapy and confidence in appropriate treatment for a majority of patients. The BinaxNOW pneumococcal urinary antigen (PNAG) test has been evaluated at laboratory level and is easy to perform and interpret, but its use as a point-of-care test has not been evaluated. A study was undertaken to assess whether PNAG testing can be reliably performed and interpreted by staff in an adult emergency department and whether rapid results influence initial treatment decisions.

Community-living adult patients presenting to the emergency department with clinical and radiological findings of pneumonia had PNAG testing performed on the same sample in both the emergency department and the microbiology laboratory in a blinded fashion. Accuracy and turnaround time were assessed. Diagnostic yield was compared with routine culture methods.

Fifty-nine patients were enrolled of whom nine (15%) had positive PNAG tests. These included three culture-proven cases and six additional cases. There was 98% concordance between emergency department and laboratory results. Turnaround time was significantly shorter when tested in the emergency department (median 2 h 39 min vs 19 h 40 min). Antibiotic prescribing was not influenced by results in this small sample.

PNAG diagnosis of pneumococcal pneumonia can be accurately performed as a point-of-care test by emergency department clinical staff. Without specific efforts to achieve early urine collection, the timeframe of testing will frequently fall outside the 4-hour patient stay of a UK emergency department and may be more appropriately considered as a test for the medical admissions unit in this setting. Sensitivity is at least equal to conventional culture methods and the result is available rapidly enough to potentially influence treatment decisions, a strategy that warrants further investigation.