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Updated: Jul 28, 2026
04:25
Capsular Serotyping of Streptococcus pneumoniae Using the Quellung Reaction
Published on: February 24, 2014
Identification of Streptococcus pneumoniae revisited
J A Kellogg1, D A Bankert, C J Elder
1Clinical Microbiology Laboratory, York Hospital, York, Pennsylvania 17405, USA. jkellogg@wellspan.org
Journal of Clinical Microbiology
|August 30, 2001
Summary
Accurate identification of Streptococcus pneumoniae is crucial. Several diagnostic assays show high sensitivity and specificity, with Phadebact, deoxycholate tube test, and optochin performing exceptionally well.
Area of Science:
- Microbiology
- Clinical Diagnostics
- Bacteriology
Background:
- Streptococcus pneumoniae is a leading cause of bacterial pneumonia and meningitis.
- Accurate and rapid laboratory identification of S. pneumoniae is essential for appropriate patient treatment and infection control.
Purpose of the Study:
- To evaluate the diagnostic performance of various assays for identifying clinical isolates of Streptococcus pneumoniae.
- To compare the sensitivities and specificities of different diagnostic methods.
Main Methods:
- Ninety-nine clinical isolates of Streptococcus pneumoniae and 101 viridans streptococci were tested.
- Assays evaluated included Pneumoslide, Directigen, Phadebact, deoxycholate drop test, deoxycholate tube test, optochin, and Gram Positive Identification Card.
Main Results:
- High sensitivities (>=99%) and specificities (>=98%) were observed for Phadebact, deoxycholate drop test, deoxycholate tube test, and optochin assays.
- Directigen showed 100% sensitivity but 85% specificity, while Pneumoslide had 99% sensitivity and 87% specificity.
- Gram Positive Identification Card demonstrated 90% sensitivity and 96% specificity.
Conclusions:
- Several diagnostic assays provide high sensitivity and specificity for S. pneumoniae identification.
- Confirmation of clinical isolates should utilize assays with well-documented high performance (>=95% sensitivity and specificity).
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