Streptococcus Urine Antigen Testing

Streptococcus pneumoniae remains the most common cause of bacterial community-acquired pneumonia (CAP) in both children and adults. Diagnosis can be challenging and relies on microbiological confirmation of S. pneumoniae as the causative pathogen in patients with clinical and radiological features of pneumonia. Respiratory and blood cultures are the diagnostic tests of choice for community-acquired Streptococcus pneumoniae. Urine antigen testing, while perhaps more convenient, carries substantial limitations.

• Urine antigen testing lacks sensitivity in adults.
• Specificity in children is low due to high colonization rates in the pediatric population.
• Test development was optimized using pre-vaccine era strains of S. pneumoniae, increasing the likelihood of missing currently circulating strains.
• Overreliance on the pneumococcal antigen test contributes to inefficient healthcare spending and potentially misleading diagnostic information.

• The 2019 IDSA/ATS guidelines do not recommend routine testing urine for pneumococcal antigen in adults with CAP, given the lack of evidence showing that urine antigen testing improves patient outcomes.
• Urine antigen testing should only be considered in adults with severe CAP, who have a higher pretest probability of having pneumococcal pneumonia.
• Respiratory and blood cultures, which provide pathogen identification and antimicrobial susceptibility test results, are recommended as the diagnostic tests of choice.

1. Falguera M, Ruiz-Gonzalez A, Schoenenberger JA, Touzon C, Gazquez I, Galindo C, et al. Prospective, randomised study to compare empirical treatment versus targeted treatment on the basis of the urine antigen results in hospitalised patients with community-acquired pneumonia. Thorax 2010;65:101–106.