Difference between S. pneumoniae and Viridans Streptococci

Difference between S. pneumoniae and Viridans Streptococci

How to differentiate Streptococcus pneumoniae and Viridans Streptococci?

There are a few ways to differentiate Streptococcus pneumoniae (S. pneumoniae) from Viridans Streptococci:

  1. Habitat. S. pneumoniae is typically found in the respiratory tract, while viridans streptococci are typically found in the mouth and throat.
  2. Pathogenicity. S. pneumoniae is a pathogenic bacterium that can cause serious infections such as pneumonia, sepsis, and meningitis. Viridans streptococci are generally considered to be non-pathogenic or opportunistic pathogens, meaning that they can cause infections in people with weakened immune systems or other underlying conditions.
  3. Antibiotic susceptibility. S. pneumoniae is generally susceptible to a wide range of antibiotics, while viridans streptococci are more resistant to antibiotics and may be more difficult to treat.
  4. Clinical significance. S. pneumoniae is considered a significant human pathogen, while viridans streptococci are more commonly associated with dental plaque and are not typically considered a major human pathogen.
  5. Laboratory testing. To differentiate between S. pneumoniae and Viridans streptococci, laboratory testing such as bacterial culture and identification can be performed. S. pneumoniae can be identified by its growth on selective media, its ability to produce the enzyme alpha-hemolysin, and its ability to ferment mannitol. Viridans streptococci can be identified by its ability to produce the enzyme Lancefield group D carbohydrate and its inability to ferment mannitol.

Overall, to differentiate between S. pneumoniae and Viridans streptococci, it is important to consider their habitat, pathogenicity, antibiotic susceptibility, clinical significance, and the results of laboratory testing.

Difference between S. pneumoniae and Viridans Streptococci

What test differentiates S. pneumoniae and viridans streptococci?

There are a few laboratory tests that can be used to differentiate Streptococcus pneumoniae (S. pneumoniae) from viridans streptococci:

  1. Bacterial culture and identification S. pneumoniae and Viridans streptococci can be cultured on selective media that allow for the growth of one type of bacterium while inhibiting the growth of the other. S. pneumoniae can be identified by its growth on selective media such as blood agar or chocolate agar, while Viridans streptococci may not grow on these media.
  2. Enzyme testing. S. pneumoniae can be identified by its ability to produce the enzyme alpha-hemolysin, while Viridans streptococci do not produce this enzyme. In addition, S. pneumoniae is unable to produce the enzyme Lancefield group D carbohydrate, while Viridans streptococci can produce this enzyme.
  3. Fermentation testing. S. pneumoniae can be identified by its ability to ferment mannitol, while Viridans streptococci are unable to ferment mannitol.

Streptococcus pneumoniae Vs Viridans Streptococci Comparision chart

S.N.CharacteristicsS. pneumoniaeViridans Streptococci
1.MorphologyLanceolate diplococciOval or round cells in chain
2.CapsuleCapsulatedNon-capsulated
3.Quellung TestPositiveNegative
4.Bile solubilityBile solubleBile insoluble
5.Inulin fermentationPositiveNegative
6.Optochin sensitivitySensitiveResistant
7.Pathogenicity in micePathogenicNon-pathogenic
8.HemolysisAlpha-hemolytic (under aerobic conditions) or Beta-hemolytic (under anaerobic conditions)Alpha hemolytic or non-hemolytic
9.PathogenesisCauses pneumoniaCauses mainly oral infections

Similarity between S. pneumoniae and Viridans Streptococci

There are a few similarities between Streptococcus pneumoniae (S. pneumoniae) and Viridans streptococci:

  • Both belong to the genus Streptococcus: S. pneumoniae and Viridans streptococci are both members of the genus Streptococcus, a group of Gram-positive, coccus-shaped bacteria.
  • Both are spherical in shape: S. pneumoniae and Viridans streptococci are both spherical in shape, with a diameter of about 0.5-1.0 µm.
  • Both are non-motile: S. pneumoniae and Viridans streptococci are both non-motile, meaning that they do not have flagella or other appendages that allow them to move.
  • Both are facultative anaerobes: S. pneumoniae and Viridans streptococci are both facultative anaerobes, meaning that they can survive in the presence or absence of oxygen.

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