In identifying Streptococcus pneumoniae, what characteristic can help differentiate it?

In identifying Streptococcus pneumoniae, what characteristic can help differentiate it?

• A. Capsulation
• B. Growth inhibition by bacitracin
• C. Optochin sensitivity
• D. Glucose fermentation

Answer: (C)

Streptococcus pneumoniae can be differentiated from other streptococci through its sensitivity to optochin. This characteristic is critical because when a culture of bacteria is exposed to optochin, S. pneumoniae is the only species among the alpha-hemolytic streptococci that shows sensitivity, leading to a zone of inhibition. This test is particularly useful in a laboratory setting for confirming the presence of S. pneumoniae in clinical specimens. The capsulation of S. pneumoniae does distinguish it from some other streptococcal species, as it possesses a polysaccharide capsule that provides virulence and helps evade the immune response. However, this characteristic alone is generally assessed through different methods and doesn't provide the specificity needed for identification when compared to the optochin sensitivity test. Growth inhibition by bacitracin is primarily a characteristic used to identify Streptococcus pyogenes, not S. pneumoniae. Therefore, it does not serve as a differentiator for S. pneumoniae. Lastly, while S. pneumoniae can ferment glucose, this characteristic is common among many bacteria and does not specifically identify S. pneumoniae, as various streptococcal species can also ferment carbohydrates. Hence, the distinguishing factor of

Streptococcus pneumoniae can be differentiated from other streptococci through its sensitivity to optochin. This characteristic is critical because when a culture of bacteria is exposed to optochin, S. pneumoniae is the only species among the alpha-hemolytic streptococci that shows sensitivity, leading to a zone of inhibition. This test is particularly useful in a laboratory setting for confirming the presence of S. pneumoniae in clinical specimens.

The capsulation of S. pneumoniae does distinguish it from some other streptococcal species, as it possesses a polysaccharide capsule that provides virulence and helps evade the immune response. However, this characteristic alone is generally assessed through different methods and doesn't provide the specificity needed for identification when compared to the optochin sensitivity test.

Growth inhibition by bacitracin is primarily a characteristic used to identify Streptococcus pyogenes, not S. pneumoniae. Therefore, it does not serve as a differentiator for S. pneumoniae.

Lastly, while S. pneumoniae can ferment glucose, this characteristic is common among many bacteria and does not specifically identify S. pneumoniae, as various streptococcal species can also ferment carbohydrates. Hence, the distinguishing factor of