Streptococcus pneumoniae is a leading bacterial cause of pneumonia globally and is the most common agent leading to hospitalization in all age groups. S. pneumoniae are gram-positive, typically lancet-shaped diplococci. It is the most frequently encountered bacterial agent of community-acquired pneumonia (CAP). Because of the significant morbidity and mortality associated with pneumococcal pneumonia, septicemia, and meningitis, it is important to have diagnostic test methods available that can provide a rapid diagnosis.
Use
Rapid diagnosis of pneumococcal pneumonia. This is a rapid immunochromatographic membrane assay that detects soluble C-polysaccharide cell wall pneumococcal antigen common to all S. pneumoniae strains. It is intended, in conjunction with culture results and clinical findings, to aid in the presumptive diagnosis of pneumococcal pneumonia.
Interpretation
Negative result: Does not exclude S. pneumoniae infection.
Positive result: Indicative of pneumococcal pneumonia. A diagnosis of S. pneumoniae infection must take into consideration all test results, culture results, and the clinical presentation of the patient.
Limitations
S. pneumoniae vaccine may cause false-positive results, especially in patients who have received the vaccine within 5 days of having the test performed. This test has sensitivity of 74% and specificity of 94%. Unfortunately, the test has poor specificity in children due to detection of pneumococcal nasopharyngeal colonization. Pneumococcal pneumonia is best diagnosed by sputum culture.