Streptococcus Pneumoniae Type 9N Capsular Polysaccharide Antigen
Streptococcus pneumoniae type 9n capsular polysaccharide antigen is a diagnostic skin test antigen used to evaluate cell-mediated immune responses to pneumococcal infection. It is primarily used as a component in delayed-type hypersensitivity testing to assess immune competence in patients, particularly those who may be immunocompromised or undergoing immunological evaluation. The antigen is injected intradermally, and a localized reaction indicates prior exposure to pneumococcus and intact cellular immunity.
A diagnostic skin test antigen used to assess cell-mediated immunity against pneumococcal bacteria.
Key facts at a glance
- RxNorm
- 854972
- Generic
- Streptococcus Pneumoniae Type 9n Capsular Polysaccharide Antigen
- Class
- unclassified
- Brands
- Pneumovax 23
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- prefilled syringe, injection, solution
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Evaluation of cell-mediated immunity, assessment of immune competence in immunocompromised patients, epidemiological studies of pneumococcal exposure, and as part of comprehensive immunologic workups to determine if a patient has mounted prior immune responses to Streptococcus pneumoniae.
When injected intradermally, the capsular polysaccharide antigen triggers a Type IV delayed-type hypersensitivity reaction in individuals previously sensitized to pneumococcal antigens. T-cells previously exposed to pneumococcus recognize the polysaccharide and release cytokines, resulting in localized induration and erythema at the injection site within 24-72 hours.
This is a diagnostic tool, not a vaccine or treatment. Results should be interpreted alongside other clinical and laboratory findings. False negatives may occur in severely immunocompromised patients. Skin testing is contraindicated in patients with certain skin conditions affecting the test site. Results may be affected by recent immunosuppressive therapy.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 31, 2026. · Read our editorial policy