Pneumococcus vs Viridans streptococci- 12 Major Differences

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Differences between Pneumococcus and Viridans streptococci

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

S.N. Properties Pneumococcus Viridans streptococci
1 Morphology Lanceolate or flame-shaped Round/oval
2 Arrangement Gram-positive cocci in pairs Gram-positive cocci in long chains
3 Capsule Present Absent
4 On blood agar Draughtsman or carom coin colony Convex shaped colony
5 Liquid medium Uniform turbidity Granular turbidity
6 Bile solubility Soluble in bile Insoluble in bile
7 Inulin fermentation Fermenter Non-fermenter
8 Optochin Sensitive Resistant
9 Mice Pathogenicity Pathogenic Non-pathogenic
10 Quellung Test Positive Negative
11 Hemolysis Alpha-hemolytic (under aerobic conditions) or Beta-hemolytic (under anaerobic conditions) Alpha hemolytic or non-hemolytic
12 Pathogenesis Causes pneumonia Causes mainly oral infections

References

  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

About Author

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Sagar Aryal, PhD

Dr. Sagar Aryal is a microbiologist, researcher, and science communicator from Nepal. He is also co-founder and Research Head of the Department of Natural Products at the Kathmandu Research Institute for Biological Sciences (KRIBS), where he leads research on natural product discovery and microbial biodiversity. Dr. Aryal earned his Ph.D. in Microbiology from Tribhuvan University, Kathmandu, Nepal, in 2025, supported by a DAAD Research Grant and a University Grants Commission (UGC) Nepal Ph.D. Fellowship. His research interests include Actinomycetes, Myxobacteria, microbial taxonomy, and natural products, particularly the discovery of bioactive compounds with potential pharmaceutical applications. He isolated and identified Nocardia nepalensis, a novel bacterial species from Nepal, contributing to understanding microbial diversity in the region. Dr. Aryal has published more than 16 research articles in international journals and contributed three book chapters to established academic publications. He has presented scientific research findings and developed international research collaborations through visits to more than 18 countries across Asia, Europe, North America, and Oceania. From 2023 to 2025, he served as the American Society for Microbiology (ASM) Young Ambassador to Nepal. Since December 2025, he has served as an Editorial Board Member of Scientific Reports, a Nature Portfolio journal. In recognition of his scientific contributions, Dr. Aryal received the NAST Science and Technology Youth Award 2025 from the Nepal Academy of Science and Technology. He previously received the Frs. Locke and Stiller Research Award (LSRA) for the 2017-2018 cycle from St. Xavier's College, Kathmandu, and a Nepal Academy of Science and Technology (NAST) Research Grant for 2017-2018. Alongside his scientific career, Dr. Aryal has more than 15 years of experience in blogging, content writing, and search engine optimization (SEO).

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