12 Differences between Pneumococcus and Viridans streptococci

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Last Updated on July 8, 2020 by Sagar Aryal

Differences between Pneumococcus and Viridans streptococci

Streptococcus pneumoniae can be differentiated from Viridans streptococci by various features:

S.N.PropertiesPneumococcusViridans streptococci
1MorphologyLanceolate or flame-shapedRound/oval
2ArrangementGram-positive cocci in pairsGram-positive cocci in long chains
4On blood agarDraughtsman or carom coin colonyConvex shaped colony
5Liquid mediumUniform turbidityGranular turbidity
6Bile solubilitySoluble in bileInsoluble in bile
7Inulin fermentationFermenterNon-fermenter
9Mice PathogenicityPathogenicNon-pathogenic
10Quellung TestPositiveNegative
11HemolysisAlpha-hemolytic (under aerobic conditions) or Beta-hemolytic (under anaerobic conditions)Alpha hemolytic or non-hemolytic
12PathogenesisCauses pneumoniaCauses mainly oral infections


  1. Apurba Sankar Sastry and Sandhya Bhat K. 2018. Review of Microbiology and Immunology. Sixth Edition. Jaypee Brothers Medical Publishers (P) Ltd.
  2. Suzuki N, Seki M, Nakano Y, Kiyoura Y, Maeno M, Yamashita Y. 2005. Discrimination of Streptococcus pneumoniae from viridans group streptococci by genomic subtractive hybridization. J Clin Microbiol. 43(9):4528–4534. doi:10.1128/JCM.43.9.4528-4534.2005.
  3. https://microbiologyinfo.com/difference-between-s-pneumoniae-and-viridans-streptococci/
  4. https://en.wikipedia.org/wiki/Viridans_streptococci
  5. https://en.wikipedia.org/wiki/Streptococcus_pneumoniae
  6. http://textbookofbacteriology.net/S.pneumoniae.html
  7. https://www.drbeen.com/blog/difference-streptococcus-pneumoniae-streptococcus-viridans/

Differences between Pneumococcus and Viridans streptococci

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