Pneumococcus vs Viridans streptococci- 12 Major Differences

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

Interesting Science Videos


  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.

Differences between Pneumococcus and Viridans streptococci

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Sagar Aryal

Sagar Aryal is a microbiologist and a scientific blogger. He is doing his Ph.D. at the Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal. He was awarded the DAAD Research Grant to conduct part of his Ph.D. research work for two years (2019-2021) at Helmholtz-Institute for Pharmaceutical Research Saarland (HIPS), Saarbrucken, Germany. Sagar is interested in research on actinobacteria, myxobacteria, and natural products. He is the Research Head of the Department of Natural Products, Kathmandu Research Institute for Biological Sciences (KRIBS), Lalitpur, Nepal. Sagar has more than ten years of experience in blogging, content writing, and SEO. Sagar was awarded the SfAM Communications Award 2015: Professional Communicator Category from the Society for Applied Microbiology (Now: Applied Microbiology International), Cambridge, United Kingdom (UK). Sagar is also the ASM Young Ambassador to Nepal for the American Society for Microbiology since 2023 onwards.

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