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Updated: Jul 28, 2026

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
Abstract:
The sensitivities and specificities of several different diagnostic assays for Streptococcus pneumoniae were assessed using 99 clinical isolates of S. pneumoniae and 101 viridans streptococci and were as follows: Pneumoslide, 99 and 87%, respectively; Directigen, 100 and 85%, respectively; Phadebact, 100 and 98%, respectively; deoxycholate drop test, 99 and 98%, respectively; deoxycholate tube test, 100 and 99%, respectively; optochin, 99 and 98%, respectively; and Gram Positive Identification Card, 90 and 96%, respectively. Identification of clinical isolates of S. pneumoniae should be confirmed using one or more diagnostic assays with well-documented high (e.g., > or =95%) sensitivities and specificities.
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